The hard part wasn’t the concrete. It was standing in a 40-foot hole on a barrier island and keeping the Atlantic out of it.
Starting the evening of July 24, Miami-based Coastal Construction Co. placed 8,400 cubic yards of concrete continuously in under 16 hours, forming the mat foundation for a planned 62-story St. Regis Residences tower in Sunny Isles Beach. ENR published a detailed account of the operation on August 3.
Getting to the Bottom of the Hole
Excavation ran roughly 40 feet below grade through saturated coastal soils. Keller North America handled groundwater control by deep soil mixing, running 6-foot augers to blend native soils with cement 60 to 70 feet down, creating a low-permeability plug beneath the excavation rather than trying to pump against the water table.
Crews installed approximately 470 auger-cast piles under the tower. Then the owner elected to install more than 100 additional piles beyond what the design required. That decision cut predicted settlement from roughly 18 inches to about 2 inches.
Eighteen inches is not a number you accept on a 62-story tower. Paying for 100 extra piles to avoid it is the kind of owner call that never shows up in a project’s marketing and determines whether the building performs.
The Pour
Roughly 1,000 ready-mix truck deliveries fed the placement. Four dedicated CEMEX batch plants supplied six boom pumps positioned around the excavation. Baker Construction was the concrete subcontractor. Every tenth truck was pulled from the queue for quality-control testing, which on a continuous pour means the logistics plan has to absorb 100 diversions without breaking the sequence.
Planning started about six weeks out. Weekly coordination meetings became near-daily as the date approached. The site fronts Collins Avenue, so the work required overnight lane closures and police traffic control. City officials asked that the placement happen after the FIFA World Cup concluded, because of visitor volume.
Crews tracked lightning within an 8-mile radius. One weather warning interrupted the pour, with about 40 cubic yards left to place. After completion the mat was insulated and wet-cured for 14 days with blankets and hosing to manage heat of hydration.
“We poured 8,400 yards in less than 16 hours. But in order to do that, we have to set up a lot of things. There are a lot of moving parts in order to make this a success,” said John DiPaula, general superintendent on the project. “The fact that we’re 40 feet in the ground on the beach, that’s what makes this unique.”
Senior project manager Nekita Whyte put the emphasis on the trade partners. “There are a lot of partnerships that have to be in place, that have to be strong to make these things successful,” she said.
Concurrently, Coastal completed a separate 1,800-cubic-yard mat placement at the Shorecrest condominium in West Palm Beach. That one used sheet piling and a wellpoint dewatering system instead of deep soil mixing, which is the more conventional answer when site conditions allow it.
Why Execution Stories Matter
Most megaproject coverage is about money. This one is about whether a plan survives contact with a schedule, and it’s a problem set that keeps growing as U.S. coastal high-rise work pushes deeper below grade on narrower sites.
The same category of work is running on the Strip, where the Hard Rock Las Vegas guitar tower topped out at 42 stories in May above an occupied podium. Different soil, same discipline: sequence everything, then don’t miss.
DiPaula’s summary was shorter. “Right people in the right roles and proper planning. We’ve done this dozens of times. We didn’t miss anything on this one.”