St. Lucie Inlet Maintenance Program

First Line Coastal staff have provided coastal engineering services for Martin County in support of maintenance of SLI since 2009 over three consecutive General Coastal Engineering Services (GEC) contracts. SLI is a federally authorized inlet with the county as the local sponsor. The project includes periodic dredging of beach-quality sand from the inlet with placement on nearby beaches north and south of the inlet. Over the past 14 years, the staff at First Line have provided support for activities pertaining to ongoing inlet management including maintenance dredging and beach nourishment.

Maintenance dredging of SLI is on a three-year cycle but is occasionally required more frequently in response to major storm events. Annual physical and environmental monitoring of the coastal system helps the County and USACE plan for future maintenance events to maintain safe navigation. Monitoring is also utilized to measure success against the established IMP and validate sand resource distribution for varying local interests.

A typical inlet maintenance project involves the removal of about 450,000 cubic yards of sand for placement on neighboring beaches, at times extending as far as 8.5 miles south of the inlet. The project is complicated by highly sensitive environmental communities and several constructability factors for traditional dredging methods. In 2013, First Line Coastal staff led production on an Alternative Analysis Study that examined dredge methods for maintaining SLI. The results of the study led to expanded design and permit options to allow for additional construction scenarios available to the project – greatly expanding flexibility with regards to timing, scale, and cost to the county. Each of the last four dredging events at SLI (2014, 2017, 2018, and 2022) have featured a unique variation in dredge methods defined by the Alternatives Analysis.

Our team also assisted Martin County with beach nourishment, survey, and construction oversight at Bathtub Beach in 2016, 2019, and 2021 under the GEC contracts. Our team’s contributions to Martin County on SLI and Bathtub Beach are terrific examples of how an advanced understanding of design, permitability, constructability, monitoring, and program management can afford our clients enhanced options in achieving their goals.