21st Century Waterfront Repair Design and Construction
Amid Chattanooga's successful downtown revitalization efforts, the city's economic development group moved forward with enhancements along the Tennessee River, effectively turning a moderately equipped boat dock into a world-class recreation area.
Named the 21st Century Waterfront Project, its cosmetic features included terraced steps from which a verdant park stretched inland, a marina, and a generous river walk with wide walkways and utility-equipped, modern moorings.
But before the project was finished, a mysterious phenomenon beneath the water's surface stopped progress in its tracks. At intermittent locations along the shoreline, the new sidewalk panels started to sink and cave in.
We were hired to investigate. What we found was causality specific to this stretch of the Tennessee River and exacerbated by dams upriver. Underwater turbulence was slowly scraping away fill material supporting the river walk's structures, including walkways and the terraced steps. Semi-annual surges from dam releases caused water levels to rise as much as 12 feet, evacuating even greater amounts of fill material from beneath shoreline structures during those times of the year.
We delivered our investigation report and were subsequently retained to perform final design and design services during construction. Our design called for the replacement of only the lowest level of terrace beams in order to facilitate the installation of sheet piles. These piles would form a wall to trap the fill material and prevent it from migrating.
Nevertheless, unexpected challenges arose. When removing the 60-foot terrace beams from the lowest level, adjacent terrace beams began to move. Supporting concrete had cracked and collapsed. Instead of replacing beams only at the lowest level of the terraced steps, we adjusted the design to replace all beams and supporting material for the terraced steps and walkways on either side, integrating the structures with the sheet-pile wall.
"We wanted to make sure the city's revitalization effort would stand the test of time," said HDR Chattanooga Office Manager Shane Womack. "We overcame some challenges, some anticipated and some not, but our strong partnership with the city of Chattanooga and understanding of its vision ultimately proved extremely successful."
The result was a stunning revitalized feature along Chattanooga's vibrant downtown waterfront with the underlying structural integrity to last for decades. The terraced steps not only beautify the waterfront at Ross's Landing Park, they serve as seating in a natural auditorium used each year during the city's famous Riverbend Festival. They also provide a vantage point from which onlookers can view activities on the water, including the city's annual Independence Day fireworks show.
This $8 million project was awarded "Project of the Year" by Chattanooga's Department of Public Works. Chattanooga Assistant City Engineer Dennis Malone called it not only "Project of the year, but also Project of the Century … the 21st Century Waterfront."
- Professional Services: Basis of Design, Charrette, Civil Engineering, Conceptual Design, Condition Assessment, Construction Administration, Construction Management, Construction Monitoring, Design Development, Design/Construction Review, Engineering & Design, Environmental Assessment, Environmental Documentation, Final Design, Geotechnical, Lighting Design, MEP Engineering, Master Planning, Owner's Engineer, Owner's Representation, Permit Assistance, Permitting, Planning, Programming, Schematic Design, Site Design, Structural Engineering, Value Engineering
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