Fort Lauderdale’s expansion from a riverfront trading post into a dense coastal metropolis placed critical infrastructure directly over the Anastasia Formation and surficial sands. Every underground project here contends with a water table barely six feet below street level and alternating layers of poorly graded sand, organic silt, and fractured limestone. Our team has managed tunnel feasibility across Broward County long enough to know that standard desk studies fail when you hit a lens of loose Miami Oolite at 20 feet. We integrate SPT drilling to map these erratic transitions before the TBM ever arrives, combining field refusal data with laboratory classification per ASTM D2487 to define stand-up time and face support requirements before the first cut.
Even a ten-foot variation in groundwater elevation can turn a stable tunnel heading into a running sand condition within minutes.
