Rotary-Driven Pipe Piles as a Solution in a Congested Dense Urban Construction Site

While New York City is known for its bedrock and being home to one of the greatest concentrations of tall buildings in the world, its soil conditions are quite variable and can be very challenging in some locations. One such neighborhood is Manhattan’s Upper East Side, particularly near East 96th Street. Historic maps show that the area was once a wetlands network of marshes and creeks. Construction projects in this area have often led to settlement of existing structures, many of which are old, low rise residential buildings supported on shallow foundations bearing on uncontrolled fill.   This case study presents the design, testing, quality control and construction of rotary-driven pipe piles for support of an 8-story medical research facility on the Upper East Side. Three hundred twenty (320) 12.75-inch diameter, rotary driven pipe piles were installed 120 feet deep. The subsurface stratigraphy consists of uncontrolled fill, organic silts, and peat over stiff, saturated, varved silts and clays. Groundwater is approximately 7 feet below grade.  The rotary-driven pipe pile does not fit neatly into any of the pile types prescribed in the NYC Building Code. Challenges were encountered developing installation criteria and a quality control program for code compliance. A “re-torque” program measuring resistance to torque and crowd-force during installation was used to verify production pile capacity and to estimate soil setup, similar to conventional driven pile restrikes.  Design methodology, torque and crowd-force measurements, load test results, and installation observations are presented. The project benefited from coordination and collaboration between the designer, contractor and special inspector during the test program and development of the final installation criteria. The rotary-driven pipe pile provides a novel “no spoils” alternative for installing deep foundations adjacent to sensitive structures. Lessons learned and potential future developments are discussed.