Opportunity
Over the course of years, the shoreline of Surfside Beach has retreated about four feet per year. From 2004 to 2006 the erosion accelerated, reaching 10 to 26 feet per year. The public beach became narrower and less safe, and public infrastructure was damaged during high tide events.
Solution
In 2007, the Texas General Land Office retained Mott MacDonald for a Shoreline Stabilization Feasibility Study to identify the causes of the erosion and suggest remedies that might stabilize the shoreline over the next 25 years.
We developed a sediment budget that includes coastal processes and man-made influences in the Surfside littoral cell. Numerical modeling was used to simulate wave transformation, wave-generated currents, sediment transport, and erosion/accretion processes.
Mott MacDonald developed a range of long-term solution alternatives, including conceptual costs for the project lifetime of each alternative. Alternatives included beach nourishment and nearshore detached breakwaters.
Beach Drive revetment
We provided preliminary design, regulatory approval, final design and construction bid documents, and engineering services during construction for a stone revetment along Beach Drive. The revetment was completed in August 2008, shortly before Hurricane Ike.
Revetment repair and enhancement
In 2011, Mott MacDonald performed an assessment of the revetment’s condition following Hurricane Ike, and designed repairs and enhancements that would bring the revetment to level of protection sufficient for a 25-year storm. Repairs and enhancement were completed in February 2011.
Beach nourishment
Also in 2011, we completed all phases of design and construction support for a beach nourishment project adding 140,000 cubic yards of sand to the shoreline. We located a suitable borrow source site and determined the service life of the project. We developed preliminary and final design plans and specifications, developed construction contract bid documents, and provided services for the bidding phase and construction oversight.
Outcome
Although the original beach revetment was severely damaged by Hurricane Ike, with 40% of the stones displaced, it nonetheless protected Beach Drive and the public water and wastewater systems, and blunted the force of the storm surge, which swept clean other nearby neighborhoods.
The later repair and enhancement of the revetment, coupled with beach nourishment, provide an even greater level of protection for the village.