March/April 2022 - 17

environmental considerations, construction took place in
phases beginning in 2016 for the bulkhead platform and
accessways, including two pile driving seasons that started in
2018, followed by superstructure construction. Construction
was completed in 2020, and the project opened to the public in
May 2021 after only a minor delay due to the pandemic.
Site and Project Challenges
The new concrete columns of Little
Island rise out of the water at the
location of the former Pier 55, and
between the wooden piles of two " ghost "
piers. These piers, the former Pier 56 and
Pier 54, are only visible now as fields of
wooden piles in the water; however, the
entrance portal to the former Pier 54 is
now preserved on the esplanade
because that pier is historically significant
as the one where surviving
passengers of the Titanic disaster
arrived to safety in 1912.
With the project goals in mind, only
those remnant piles were removed that
obstructed the new piles; the remainder
were left in place to serve as marine habitat and physical
protection of the pier. The bulkhead platform and the
accessways, constructed by Trevcon Construction, are
supported on 24 in sq (61 cm sq) precast, prestressed concrete
piles for storm resilience. The two
accessways connect the pier to a new
esplanade over the bulkhead platform,
with the esplanade extending from
Gansevoort Peninsula to the south and
Pier 57 to the north.
The devastating effects of 2012's
Hurricane Sandy on the New York City
waterfront also affected the design of
Little Island. Its original design had the
pier being constructed over and within
the footprint of the old Pier 54. However,
the design was changed to raise the pier
height and to design an interior, flat precast
concrete slab to harden the overall
pier; this slab also reduced the cost of
creating concrete pots.
Creation of the concrete slab and the
pots that hold the park elements and
landscaping, as well as the complex
subsurface conditions that were identified,
provided added challenges.
Although Little Island can appear to be
floating, the 300 ft by 300 ft (91 m by
91 m) park is supported by 267 precast
topography of man-made hills. The final elevations vary
between +11 and +63 relative to mean high water (MHW). This
structural approach provides visitors with unique views of the
Hudson River and New York City.
Arup, the structural engineer, designed
the pot elements in the superstructure
that range from 10 to 30 ft (3 to
9 m) in height. One hundred thirty-two
individual precast concrete column
heads are each fitted to have 4 to 6
precast concrete petals (655 total);
precast concrete planks span between
the petals and column heads. Cast-inplace
edge beams and a topping slab
connect the adjoining pot elements and
provide rigidity to the overall structure.
Because the concrete tulip pots atop
Concrete composite pile details
each of the outer-rim piles are all
different, they were formed from precast
concrete " petal " sections that were
fabricated and assembled offsite to
exacting standards. Besides the petal
segments, an internal structure and a
column head connects each pot to its
unique composite pile. The pots were
fabricated by the Fort Miller Company at
their Easton, New York, concrete plant,
then assembled and floated down the
Hudson by barge, four at a time. Each pot
DEEP FOUNDATIONS * MAR/APR 2022 * 17
concrete composite piles designed by MRCE. They are of 36 in
(91cm) diameter and of varying lengths. The central concrete
slab area is supported by 135 composite piles. As part of the
aesthetic vision of the new pier, the 132 remaining composite
piles rim the pier and are each topped by tulip-shaped pots that
hold the park elements and landscaping. These pot-topped
piles are set at different heights to create an undulating
Side view of dual-purpose, composite piles
March/April 2022

Table of Contents for the Digital Edition of March/April 2022
