The City of Jacksonville, Florida has the largest urban park system in the US. Enhancing its dynamic network of outdoor community spaces, the city is adding numerous docks along the St. Johns River for visiting boaters and water taxis. The new Post Street location in the historic Riverside neighborhood presented several engineering challenges that were easily overcome when the city chose a state-of-the-art SF Marina floating concrete dock array.
The Post Street boat landing site not only contends with a fast-moving river current, but also strong southerly wave action. Coupled with the location being directly adjacent to underground utilities, the dock structure had to be built rock-solid to remain in place if a hurricane were to hit the area. The city specified that it would need to withstand 193 kph winds for two hours with 3m storm surges.
Jacksonville-based Hal Jones Contractor, a division of Vecellio & Grogan, Inc., installed the two-part 29m L x 3m W SF1230 HD pontoon and three SF1224 9.7m L x 2.4m W fingers. The sections are joined together using SF Marina’s exceptionally reliable connector system that absorbs torsional tension and heavy loading. The array is designed to accommodate six vessels up to 15m in length.
To secure the structure, Hal Jones Contractor drove eight 0.5m steel piles over 12m deep into the rocky river bottom. This safeguards against the array moving and damaging the utility lines. Custom guides allow the pontoons to rise and fall smoothly with water level changes.
Engineered with uncompromising strength for heavy commercial use, 1200-series SF Marina floating concrete pontoons have substantial mass and weight. Combined with a wave-dampening design, this makes them exceptionally stable. The dock array connects to the shoreline via a 12.8m L x 1.2m W aluminum bridge and 11m L x 1.2m W hinged gangway.
Concrete pontoons for the structure were manufactured in SF Marina’s Norfolk, Virginia facility and trucked to Jacksonville. The Post Street project was the first SF Marina system installed by Hal Jones Contractor. “We were impressed,” said Greg Tolbert, Hal Jones Contractor project manager. “After two months of use, the docks are performing as planned and we’ll certainly consider SF Marina when looking at future jobs.”