Project

The project consisted of a new twelve-story apartment building in downtown St. Petersburg.

The Problem

The geotechnical investigation found two distinct layers of loose sands. The first layer was in the upper twenty feet of the soil profile and the second was located deeper beneath a competent soil layer. The proposed structural loading of the apartments would lead to excessive settlement in both layers. The geotechnical engineer recommended a deep piling foundation system to support the structure.

Earth Tech Solution

As an alternate to a deep pile foundations, Earth Tech proposed and implemented a targeted solution, where wet top feed  Vibro Replacement was used to densify the loose sand layer up to depths of twenty feet and Low Mobility Grouted Rigid Inclusions (LMGRI’s) were used to target the deeper loose layer from thirty to fifty feet. The sands were adequately densified and reinforced in each zone, settlement controlled, and shallow foundations were designed and installed utilizing a bearing pressure of 6,000 psf.