Little Island Sculptural Precast Concrete Pots Project, New York, NY
Precast Concrete Sculptural Pots play prominent role in Pier- Park Hybrid
On May 21, 2021, Little Island welcomed tourists and residents to New York City’s new park-pier hybrid that has been in development for over a decade. Little Island, formerly known as Pier 55, is located along the Hudson River on the far west side of Manhattan near 13th Street. From a distance what looks like a field of giant white tulips that rise high above the river, are actually 132 precast concrete cup-like pots atop individual pilings. The varying heights of the precast concrete piles create the illusion of an undulating wave.
At a cost of $250 million, the Hudson River Park Trust was funded by husband and wife Barry Diller and Diane von Furstenberg. Planning for the project began in 2012 and construction started in 2018. The hilly landscaped refuge will offer visitors walking trails, a public plaza, and performance stages, among other recreational spaces. Delineating these uses will be a wide variety of native flora, ranging from dozens of tree and shrub species to hundreds of types of grasses and perennials, all nestled atop the giant concrete “tulip pots”.
Eye catching feature
The 2.4 acre park creates a magical space on New York City’s riverfront. At its highest, the pier-park hybrid is 62 feet above the Hudson River. Little Island is angled off the waterfront to both frame views of the Manhattan skyline and the Statue of Liberty and capture greater solar exposure.
The pots, which look like flower petals are the most eye catching feature. The term is appropriate since the fabrication of the giant cups includes putting together pieces that are called petals. Precast concrete was selected for the project for its resistance to corrosion, salts and other elements common to a marine location.
Although they appear to be one piece, the piles and pots were fabricated by different firms in different places. The precast piles were produced by Coastal Precast in Chesapeake, Virginia. Coastal Precast fabricated the precast prestressed concrete piles and barged them to Pier 55 where they were driven into the Hudson River bedrock.
Pile work required planning and precision. The project includes a total of 267 piles, including those for the flat lower pier underneath the pots. They each support 250 to 350 tons. The constrained size of the site and seasonal fish migration mandated gaps during installation. Environmental restrictions allows work on the Hudson River to be conducted only between May and December. So 164 piles were driven almost 200 feet below the river during that phase in 2018. The team then installed the first set of pots during the off-season. The remaining 103 piles were installed from May through July of 2019. The varying heights of the new concrete piles – the tallest reaches 62 feet above the Hudson, allows sunlight to reach marine habitats.
After the design competition, the concept from London architect Heatherwick Studio was selected. The rest of the team was assembled which included Structural Engineer, Arup, The Fort Miller Co., Inc. as precast fabricator, Mueser Rutledge Consulting Engineers for marine engineering, Standard Architects as Architect of Record and Hunter Roberts Group as Construction Manager.
While some were skeptical about the feasibility of using precast concrete for this elaborate concept, Fort Miller was up to the challenge. In addition to the unusual shape and size of the precast concrete pots which were depicted on 3D models, the drawings specified very few dimensions.
“This was one of, it not the most challenging, structural precast concrete project that we have ever been involved in, but also one of the most rewarding and collaborative projects, we have ever done in our 73 years in the precast concrete business’” recalls Joseph O'Malley, Sales Engineer, The Fort Miller Co., Inc.
The Fort Miller team used 39 sets of formwork made through 3D computer modeling to create the 132 pots. Then they could re-use some of the forms and depending on the vertical plane of each pot, pour varying petals, approximately four to six for each cup.
The craftsmen used a robotic milling machine to create foam models of every pot piece, then laid the pieces on the floor of a 600-foot long building that was cleared out for the job. They used an automated laser cutter and folded them like origami into the right shapes, coated them and then cast them in concrete.
In order to avoid building rows of columns in straight lines, a tilting geometric repeating pattern was used and the massive containers were stretched upward at varying heights.
Because of their sheer size, an individual pot can weigh up to 90 tons and be up to 30 feet tall, they could not be assembled at the shop. A total of 655 individual petals were transported by truck from Fort Miller’s Schuylerville NY facilities to the Port of Coeymans on the Hudson River just south of Albany.
Weeks Marine then took custody of the pieces, assembled them, welded the stainless steel connecting plates and used a gantry crane to load four complete pots onto one barge for the ride down the Hudson River to the jobsite in Manhattan. Placement required extreme precision because the pots were designed to be 12 inches apart with a 3-inch tolerance.
After placing the last pot on the final piling, the team’s work was not yet complete. A park had to be created on top of the cups. An extensive irrigation system needed to be up and running early to ensure trees, plants and shrubs didn’t die before the park was finished. Geofibers were placed in the soil for slope stabilization as the maritime botanical garden was planted. North and South Access walkways connect Little Island to the river’s edge, and the flat, more conventional portion of the park.
After quarantine conditions during the pandemic, New Yorkers will revel in this new outdoor public space. Little Island’s unique and innovative construction provides that and more and the New York landscape will be forever changed with its precast concrete stage.