Kennedy Space Center Bridge Scour

A bridge scour project at the NASA Kennedy Space Center (KSC) in Cape Canaveral, Florida, required a remedial and protective solution. Continuous scour protection was needed around each bascule pier for four bridges throughout KSC's channel and fender system. Positioning and anchoring the mats were also significant challenges. "The Haulover Canal Bridge, in particular, has a narrow channel, which has high velocities and deep scour pockets," said Kim Rivera of Jones Edmunds & Associates, Inc., the design engineer of the project. 

The project involved installing the geosynthetic revetment system at depths of approximately 20 feet, amid high water velocities and with limited overhead clearance. Narrow channels, strong currents, and deep scour pockets demanded dredge and fill maneuvers or anchoring systems for slopes greater than 2 to 1. 

"There is extremely low visibility at all bridge and high velocities...These bridges provide the only access into KSC and were required to remain open to street traffic," said Rivera, who added that there were strict requirements regarding vessel closure times and channels depths.

Bank & shore riprap presented an alternative solution, but its 3.6 foot thickness would have required excessive channel dredging to ensure proper, USACE-approved depth. Articulated concrete block mats had a much higher cost compared to Triton Marine Mattresses and could not be custom fit around KSC's fender system.

Triton Marine Mattresses were selected for their constructability, adaptability and durability in a challenging, submarine environment. Also, the coastal and waterway revetment system was much more cost-effective than the alternatives.

Additionally, Jones Edmunds & Associates, Inc., selected Triton Marine Mattresses because:

• They incorporated Tensar uniaxial (UX) geogrids, which have the strength and flexibility to armor the bridge piers without damaging them.
• The armor units could be locally constructed and customized on shore prior to installation.
• They could provide the most efficient bridge scour protection at less than half the thickness of riprap, an even bigger benefit for material-conscious NASA.
• They are much easier to remove than riprap, a factor the agency had to consider given the potential for future bridge replacement projects.
• They offered a one-foot profile that minimized transition from surrounding riprap grades.
• They were constructible even in difficult working conditions.