Increasing resilience for coastal environments often requires working with altered ecologies resulting from the interaction of natural and man-made conditions. In the 1950’s the Mississippi Gulf Coastline was altered by the construction of a seawall and the creation of a 40 mile man-made beach replacing a complex natural shoreline of tidal marshes, inlets and sand coves all buffered by the barrier islands that protect the Mississippi Sound. Along with the seawall and beach came over 200 outfall culverts transporting storm water from upstream neighborhoods to the sound, passing under the beach highway and the beach and extending out into the water. These outfall culverts are located at the end of nearly every neighborhood street. Posted danger signs on the culverts contribute to the public’s common misunderstanding that the outfalls are sanitary sewer drains. Nevertheless, even as storm water, the outfalls bring with them everything that is washed into the drains after a storm including trash and the fecal bacteria that lead to beach closures. In addition to the water quality problem the culverts are impacted by high tides and sea level rise. Large storms, especially when combined with high tides or storm surge inundate the culverts flooding the beach highway.
Results/Conclusions
Challenge” a design completion to design and implement pilot projects for resilient alternatives to the outfall culverts. Mississippi State University’s Gulf Coast Community Design Studio, was part of a team along with Moffatt Nichol - a national engineering firm, and marine scientists from both MSU and USM. The MSU team’s proposal was one of three winning projects selected through an extensive review process to be developed and implemented. The presentation will show how the project combines engineering and ecology with a ground water draw-down system that filters and manages the water that flows to the beach, and downstream a protected tidal marsh to further cleanse the storm water and a natural sand cove to connects to the sound. Offshore the salvaged culverts are reused to enclose an oyster garden. The design illustrates how engineering is used to create the water flow needed to sustain a living ecosystem and how the entire outfall is made to replace the unsightly culvert with a man-made “natural” environment that uses ecosystem services and invites the public to learn and experience a resilient system.