Ossabaw Island, located 20 miles South of Savannah Georgia, is an island in the truest sense of the word. With no bridges, there is no access other than by water. This provided many challenges for the installation of two 100’ telescoping data monitoring towers. Savannah’s own, BRW Construction, contracted with Mount Valley Foundation Services of Columbia, SC, for the project. Mount Valley, was chosen over other regional contractors because of their 25 plus years experience installing deep foundations and tension anchor/tiebacks and their ability to create solutions for challenging applications. Mount Valley along with Dan’l Moulton, P.E., Principle with Moulton Clemson Jones, Inc. of Bluffton, SC, designed a deep helical pile foundation that could meet the strict requirements of the project engineers and the owners.
The project required a 6-hour barge ride to the Island through dozens of channels and open water. Once on the Island, Mount Valley installed two groups of six helical piles each at two separate locations on opposite ends of the island. The groups consisted of 3-30 kip compression piles closely grouped to support the tower base and 3 individual 20 kip tension anchors for the guy wires to attach through a specially designed clevis. Beyond the special mobilization requirements, special attention had to paid to precise horizontal angle and rotational angle installation.
All of the piers were installed using a Bobcat T300 track steer powering an Eskridge 70-28 model drive motor. All installation torques were monitored with a ProDig Model C440 torque transducer. The ProDig equipment was wirelessly monitored with a handheld monitor by the project foreman. The deep helical foundation installation was completed in less than two days and the towers were erected and operational in less than a week. Mount Valley Foundation Services was proud to be chosen to provide a “rock solid foundation” for such an unusual and important project as the Ossabaw Island Barrier Island observatory.