Building A Park Above A Blazing Hot Pit Is As Complicated As It Sounds

Building A Park Above A Blazing Hot Pit Is As Complicated As It Sounds

It can get as hot as 65.5 degrees. There’s no arable soil to support life. And water? Water is complicated. This isn’t humanity’s quest to terraform an exoplanet. It’s New York’s plan to build a park above a train yard.

Hudson Yards, a $US20 billion development underway in Manhattan this year, is destined to become the largest private development in US history. As we wrote last year, most of the new neighbourhood is being built above an open pit that’s home to a working rail yard, which has necessitated the construction of a gigantic steel foundation to support several skyscrapers and other buildings that must “float” over the pit.

It’s an unbelievably excessive and interesting project, a prime example of Manhattan’s luxury real estate boom. And while we’ve heard quite a bit about the residential towers and commercial buildings being built, it wouldn’t be complete without a park. That seemingly simple amenity has proven more difficult than throwing down some sod and installing a swing set. The developer behind the project has shared a few details about the construction of the green space, which sounds so difficult and expensive to build that it may as well be on Mars.

For example, the yard gets hot. Very hot: A “scorching 150 degrees Fahrenheit (65.5 Celsius), creating soil conditions too hot for tree survival.” Then there’s the soil issue, which is complicated since the park will rest on a steel foundation. As the landscape architect behind the project bluntly put it to The New York Times a few weeks ago, “we have no soil.” Not to mention natural drainage.

Related, the developer explains how they will deal with these issues with a handy graphic. Let’s start from the bottom up: First, below the actual ground level, you’ve got active train tracks that take Amtrak trains to and from New Jersey under the Hudson. Then you’ve got the above-ground train yard, which is used to store Long Island Rail Road trains moving to and from the city every day. Caissons punched into the rock around the tracks support the steel structure that holds up Hudson Yards, thanks to a bridge-like series of steel trusses that are currently being constructed.

That’s where things get interesting. In the plenum space between the steel beams and the soil below the park, the developer is installing 15 gigantic fans — “commonly used in commercial jet engines” — to circulate air and cool the space:

It will also install a wide mat of tubes circulating cooling liquids to keep the soil and roots cool enough to support life, a system not unlike a radiant heating or cooling system installed below a home’s floorboards.

The soil itself, even if it stays cool, is a big challenge too — plants naturally put down roots deep into the soil, but they won’t have the chance at this park, since there’s only room for about 18 inches of soil or four feet where trees are planted. The developers say they’re working on “a specially engineered ‘soil sandwich’ of sand, gravel and concrete slab to protect the roots while allowing them to expand.” Meanwhile, a 60,000 gallon rainwater collection system embedded in the plenum will catch and recirculate water to the roots.

It’s a lot of technology for what will be a small park, but that’s sort of the theme of Hudson Yards itself. As we’ve said before, it’s the latest example of how ever-rising property values in New York have inspired radical technological solutions to creating more land. In the 1600s, it was expanding the city’s footprint by infilling the Hudson. In the 2010s, it’s building new land over the existing city.

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