Luxury Living on the Beach in Coney Island, Brooklyn An Engineer's Solution to Make Developer's Dream a Reality-PPT Presentation

PPT Presentation

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The presentation describes the foundation design for a luxury residential development occupying a full city block in Coney Island, Brooklyn. The project includes two 20- and 22-story towers above a 3- to 5-story podium, on a site near the boardwalk and within a FEMA flood zone.<br /><br />Although earlier investigations found fill over medium-dense sand and suggested shallow foundations might work, a more extensive subsurface study was undertaken: 16 deep SPT borings, eight CPT soundings, groundwater wells, and test pits. It revealed a complex sequence of sand and soft organic clay layers extending to significant depths. The deeper clay would have been missed by investigations limited to minimum code requirements. Flood conditions, clay consolidation and downdrag, and the towers’ much greater column loads made foundation design particularly challenging.<br /><br />The team used CPT and SPT data to assess pile capacities and evaluated open-ended steel pipe piles and H-piles. Load testing—including static compression and lateral tests, dynamic testing, and CAPWAP analyses—helped confirm design assumptions and refine production recommendations. The final solution matched foundations to building loads: the towers were supported on 16-inch-diameter, 170-foot-long open-ended steel pipe piles designed for 150 tons each, while the podium rested on shallow spread footings bearing on sand at 3 tsf. Predicted differential settlements were less than one inch.<br /><br />A total of 591 production piles were installed using three driving rigs. The project demonstrates the value of understanding local geology, investigating deeper than minimum requirements when conditions warrant, and conducting load tests before full construction. The upfront investment in subsurface exploration and testing helped optimize the foundation system and could reduce construction costs.

Keywords

foundation design

Coney Island

Brooklyn

luxury residential development

deep foundation

steel pipe piles

subsurface investigation

flood zone

load testing

differential settlement