H&H is providing emergency engineering design services for the restoration of the Sanibel Causeway, which suffered extensive damage during Hurricane Ian in 2022. A combination of structural failures of the existing mechanically stabilized earth (MSE) retaining walls, anchored concrete sheet pile seawalls along the bridge approaches, and large full breaches of the earthen causeway and roadways between the bridges prevented vehicle access to Sanibel Island.
This project was performed under an emergency progressive design-build contract executed by a joint venture with engineering design services provided by H&H as a subconsultant.
Under the project’s initial phase, temporary repairs restored emergency vehicle access to Sanibel Island in only six days after receiving Notice-to-Proceed. This was accomplished with more than 1,000 trucks of earth fill placed along the failed retaining walls with side slopes stabilized by temporary sheet pile walls along the toe of slopes. Breaches in the causeways were restored with the earth fill. This work was immediately followed by armoring the initial repairs with limestone rip rap to maintain the integrity of the temporary embankments and to establish safe conditions for the general public until more permanent repairs could be designed and constructed.
Currently, in progress, the final phase consists of the design and construction of new permanent steel sheet pile walls and steel combination walls with limestone rip rap scour countermeasures designed for future corrosion in the extremely aggressive marine environment and for protection against future major coastal storm events. Protection of the earthen causeway and roadway between the bridges from future scour and undermining consists of a combination of buried steel sheet pile walls and marine mattresses along these features.
H&H collaborated with the contractor joint venture team, FDOT District 1 and Central Office, and our design partner to identify and understand the causes of the damage, design temporary repairs that could be rapidly constructed to restore service to emergency services and the general public as quickly and safely as practical, that could be implemented in a manner that permitted the construction of economical and durable permanent repairs.