BY-PASS HIGHWAY, CROSSING A SWAMP
An Engineering Excellence Award-Winning Project

The Conway By-pass is a four-lane, limited-access highway routing heavy traffic away from the busy resort areas of Myrtle Beach, South Carolina. Nearly four miles of this freeway crosses Long Bay Swamp, a pristine Carolina bay, on an earth-fill embankment 8 to 12 feet high.

S&ME faced major challenges when retained by Fluor Daniel Infrastructure to provide consultation on geotechnical design of foundations and embankment, including field recommendations for undercutting and stabilization of embankment fill areas as operations proceeded.

Instead of the typical approach of undercutting and mucking out the unstable layers of vegetation and sands, S&ME recommended bridging the surface with a geogrid layer to reinforce the base of the fill embankment. The approach minimized the impact on surrounding wetlands and reduced time, equipment and labor costs. S&ME demonstrated on a massive scale the applicability of aggressive use of synthetic reinforcing materials to improve the stability of poor subgrade soils in such a situation.

This project lead to S&ME becoming a part of the team selected by the Utah Department of Transportation to design the Legacy Parkway in Salt Lake City.