Keller has worked on previous phases of the casino and on other Hard Rock properties - including those in Coconut Creek, Tampa and Louisiana. This latest development by the Seminole Tribe, which owns the flagship hotel and casino, includes what is claimed to be the largest pool area in the Caribbean, plus an expanded casino and new show venue.

Keller's project scope involved designing and building the foundation support system for all of the proposed new buildings, but the team faced significant challenges. "The area was very swampy and peaty, with deep lakes and poor soils," explained HJ Foundation vice president Andres Baquerizo. "A lot of the work also had to be carried out in low-headroom areas."

Keller company HJ Foundation designed and installed all of the piling work on the main hotel tower, as well as for a smaller, poolside tower, the Hard Rock Live stadium and for the low-headroom areas of the valet tunnel connecting the garage to the casino.

The latter was located beneath an existing garage in a confined area with just a 16ft vertical clearance in places. Fellow business unit Hayward Baker constructed 15ft-deep gravity walls (between five and 10ft thick), using wet-soil mixing. Excavation support in open headroom switched to sheet piles. But not only did the team have to contend with low headroom within the garage, they also had to work next to and beneath a US$8 million, 200ft-long television screen, curving around the car park.

Multiple techniques were combined to act as one excavation support system. "Traditional sheet piling couldn't be completed in the low-headroom areas, so we constructed the soilcrete gravity walls," said Jeremiah Filjones, Hayward Baker senior project manager. "We used speciality batching and soil-mixing equipment to create in-situ soilcrete into which we installed driven H-piles. Once we'd cleared the garage area and television, we were able to install a sheet pile earth-retention system using traditional pile driving."

Sheet pile lengths ranged from 17 to 40ft, with micropiles used under the low-rise structures as deep foundations. Once the tunnel excavation began, the team installed internal bracing along the top of the sheet-pile system.

Other Hayward Baker techniques included using vibro-compaction, vibro-replacement/stone columns and compaction grouting to increase the bearing values on the shallow foundations for the low-rise structures, and augercast piles installed by HJ for the deep foundations of the main tower.

While Hayward Baker and HJ Foundation were focused below ground, another Keller business unit, Suncoast Post-Tension was bringing its expertise to the main hotel tower.

Suncoast supplied 700,000ft of encapsulated unbonded post-tensioning materials and 5,000 Suncoast SRS (stud reinforcement system) units for the 485,000ft² of 9in elevated floor slabs. The Suncoast SRS assemblies provide an economical and easy-to-install solution for providing punching shear reinforcement in the thinner slabs that result from the use of post-tension reinforcement.

"There were two main core areas in the hotel itself where the post-tensioning tendons couldn't be stressed, so our engineers had to provide a construction sequence that facilitated stressing the tendons from outside of these areas," said Suncoast regional sales manager Raymond J Bontz. "We also had to provide very detailed drawings of our anchor system for the BIM [building information modelling]. You can't have anything that would interfere with the glass facade of the hotel, so we had to create in-depth details of the anchorages which in BIM would show any potential conflicts with the facade embeds, so the anchorage locations could be adjusted if required."