COVER STORY USTA Geoseismic and Foundation Design Challenges View inside stadium during roof construction (photo credit Srinivas Yenamandra) The United States Tennis Association (USTA) Billie Jean King National Tennis Center (BJKNTC) site is located in the northeastern portion of the Flushing Meadows Corona Park area of Queens, N.Y. The site occu- pies some of the most difficult subsurface conditions for construction in the New York City (NYC) metropolitan area, with unique challenges from geotechnical, seismic and foundation design perspectives. At the USTA site, Paleozoic crystalline bedrock is found at a depth of roughly 300 to 400 ft (90 to 120 m) below grade. The geologic history of the site is complicated, starting from the early Pleistocene, when the ancient Hudson River temporarily changed course, flowing across Queens enroute to the Atlantic. It eventually carved a deep valley through the Cretaceous soils, in some places all the way down to bedrock. A series of glaciers advanced and retreated across the region during the Pleistocene times, filling the deep valley with layers of assorted glacial soils. At its southern edge, the last major glacier to flow across the region built up a ridge at the southern tip of Flushing Meadows known as the Harbor Hill terminal moraine. This ridge blocked the valley forming a dam, so as ice started melting away the valley filled up with a lake fed by glacial meltwater. Layers of clean outwash sand and varved silt and AUTHORS clay filled the glacial lake. The ice did not retreat in a steady manner, instead periodically readvancing over the previously deposited soil in the lake, then retreating far enough to let the lake drain temporarily into Long Island Sound, before readvancing again. As a result of this repeated sequence of retreat, advance, retreat, etc., there are places where a “crust” of desiccated soil formed when the lake drained, and areas with interlayers of outwash sand where ice readvanced into the lake. When the ice melted north of Long Island Sound, the glacial lake filling Flushing Meadows drained forming Flushing Creek. During the Holocene (roughly the last 11,000 years), as ice melted further away and sea-level rose, low lying areas filled with river sands and marine clays, along with coastal marsh deposits. Table 1 lists the soil design properties on site and Figure 1 exhibits the geologic section across the site. In the early 20th century, Brooklyn Ash Co. had a contract to fill the marshland with coal cinders. Subsequently, the site was used for the 1939 World’s Fair and reused for the 1964 World’s Fair with successive filling each time. The USTA moved to the site in 1978 and in the mid-1990s constructed the 23,000-seat Arthur Ashe Stadium (AAS) that replaced the existing field courts at the time. Athena C. DeNivo, P.E., Pablo V. Lopez, P.E., Sissy Nikolaou, Ph.D., P.E., and Alfred H. Brand, P.E., Mueser Rutledge Consulting Engineers, Rudivien G. Josef and Ahmad Rahimian, Ph.D., P.E., S.E., WSP Group 14 • DEEP FOUNDATIONS • SEPT/OCT 2015
