Thomas Heatherwick’s 2.4-acre, $260 million Chelsea Park at Pier 55, (aka Little Island) is an elevated park built on piles. The “island” was conceived by Thomas Heatherwick, an English designer and founder of Heatherwick Studios in London, to resemble a leaf floating on water.
As a subcontractor to Weeks Marine, Inc., GZA’s Contractor Services Division managed the pile testing for this iconic waterfront park development. Prior to performing the work GZA prepared a qualifications submittal for review and approval by the Engineer and a WEAP analysis submittal, per pile type, to evaluate the proposed pile driving system. GZA provided select equipment, labor, and miscellaneous materials to perform dynamic pile testing according to project specifications and ASTM D 4945 - Standard Test Method for High-Strain Dynamic Testing of Piles. GZA completed dynamic pile load testing on 36-inch diameter concrete cylinder test piles with W-section stingers and 24-inch square precast prestressed concrete test piles. The test piles required dynamic testing during initial drive and restrike, following a minimum setup period of 48 hours. Pile lengths for the concrete piles driven into highly variable overburden materials and a sloping mica-schist bedrock ranged from 93 to more than 260 feet across a span of 300 feet. Pile damage due to overdriving was a concern for the early pile installations on the east side which had quick drive times, so the refusal threshold was closely monitored and adhered to by GZA and Weeks Marine. The west side of the park experienced much slower drive times due to the geology and the deeper pile depths required. One CAPWAP analysis was performed on each test pile after each phase of testing (initial drive & restrike) and reports summarizing the test results were submitted. Also, GZA performed a refined WEAP analysis submittal for review and approval.
Through the development on an inventive solution to a once dilapidated pier, residents and visitor of New York City can now enjoy a waterfront destination featuring over 100 kinds of plants, iconic views, walking path, and a 700-seat amphitheater. Piles from the demolished adjacent and dilapidated Piers 54 and 56 were intentionally left in place to shelter aquatic life.