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Non-Rock Alternative to Shoreline Protection (LA-16)

Project Overview
Royal performed design-build services for a shoreline protection demonstration project for the Natural Resources Conservation Service (NRCS). The goal of this project was to test a non-rock alternative to shoreline protection that could be supported by low bearing-capacity soils and also attenuate wave energy over a twenty-year design life, thereby reducing, eliminating, or reversing shoreline erosion.

Project Work and Royal Solutions
To meet the objectives of the NRCS for this project, Royal developed a concept for a series of pile-supported panel structures to serve as a non-rock breakwater. The panels were perforated to allow tidal exchange while still providing a barrier for dissipating wave energy. To assess the potential performance of these structures under wave attack, Royal conducted site-specific three-dimensional modeling of the structures with the software Flow3D to evaluate wave energy transmission through the panels, assess total wave force on the structure, and estimate scour depths around the piles. Critical system parameters were optimized within the numerical model including the panel porosity, wall spacing, and the submergence depth of the panels within the water column. Additionally, Royal performed the structural engineering for the panels, connections, and supports to achieve both a structurally sound and easily constructible product.

The wall panels for this system were constructed of marine-grade ultra-high molecular weight polyethylene and encased within prefabricated steel jackets for connection to circular steel pile supports. All steel components were coated with marine-grade polymer coating for corrosion and UV resistance. Three years of monitoring indicated that Royal’s system realized a positive 126% shoreline change rate and attenuated 83% of wave action. The system was named the Wave Screen System (WSS).

The WSS installation was monitored for three years by CWPPRA against three other designs and a reference site from May 2014 to April 2017. The WSS ranked first in all three monitored categories of Soil Volume Change Rate, Shoreline Change Rate, and Wave Attenuation. The U.S. patent for this product is pending, under the ownership of Integrated Shoreline Solutions, LLC.