The canopy above one of the skating rinks at the LeFrak Center at Lakeside, in Brooklyn’s Prospect Park, measures 108 by 240 ft. A series of curves etched into the underside of the covering mimics the compulsory forms formerly required in the sport of figure skating. © Michael Moran/OTTO
Two connected ice skating rinks have been added to Prospect Park in Brooklyn. The rinks’ low profiles and multiple possible uses pay respect to the park’s original landscape architects, Fredrick Law Olmsted and Calvert Vaux.
February 11, 2014—Historic Prospect Park, the 585-acre greensward in central Brooklyn designed by famed landscape architects Fredrick Law Olmsted and Calvert Vaux, dates to 1867. It’s sacred ground for Brooklynites, and little new has been built in the park for decades. Until now: late last year the park replaced an old skating rink that dates to the Robert Moses mid-century era with a new pair of hockey and skating rinks designed by Tod Williams Billie Tsien Architects (TWBTA) and landscape architect Christian Zimmerman, both based in New York City. The $50-million, 75,000 sq ft project, formally known as the Samuel J. and Ethel LeFrak Center at Lakeside, is part of a $74-million, 26-acre overhaul of the nearby park region, including the restoration of the shoreline of its 60-acre lake.
Turns out the park was sacred ground for designers, too. “We were daunted by it, because of how rare it is to build in an Olmstead park,” says Andy Kim, an architect with TWBTA. “It’s arguably Olmstead and Vaux’s best park. Brooklynites like to say Central Park is where he practiced his craft and then he perfected it 10 years later at Prospect Park.”
Kim, a resident of Park Slope, which borders the park, says he lobbied hard within his office to manage the project when the firm came onboard in 2006. The architects of TWBTA may seem an odd choice to design a facility for the park, since they are not known for work with historic designs, but the firm was determined to respect the pastoral setting of Olmsted’s vision. “When you get a chance to do a commission like this, in a context so rich with history and so beautiful, you sense that integrating with the site is a mandate,” says Kim. “While we’re not historical stylists, we figured we better not flub up the beauty of the area with something too objectlike or distinct.”
When the firm began the project, it was dealing with a master plan that dated to the early 2000s. The project was initially slated for 35,000 sq ft, which called for an interior hockey rink with support spaces and an exterior pad placed near the lake; the massing of the project was what you might find in a suburban municipal facility. “We were compelled to try to back them off of that,” Kim says. For one thing, the main rink wouldn’t be connected very well to the surrounding park. And the original feasibility plan also called for a vehicular drop-off and a surface parking lot, both of which were antithetical to restoring Olmsted’s vision.
The LeFrak Center at Lakeside is the first new structure in
Prospect Park in decades. The center offers ice skating and
hockey in the winter, and roller-skating and an outdoor water
plaza in summer. © Michael Moran/OTTO
Eventually the program grew to include an Olympic-size rink, changing rooms for hockey teams, and even kennels, as different stakeholders around the park aimed to be part of the new project. But the recession ground the project to a halt. Had the bubble continued, successful fund-raising might have put that initial, more comprehensive vision on track. “Those schemes were very different in massing and appearance,” says Kim. “It just would have been a very different proposition. It might have been quite successful, but in a very different way.”
In the wake of the recession, though, the building’s program was reduced to the essential element—the rinks—and gained a sense of modesty in its interaction with the land. Both rinks were moved outdoors, and the L-shaped building that framed them was reimagined as a single-story structure, buried in the earth; it’s difficult to detect the structure when approaching from the east and north, thanks to berms of earth fill. One canopy floats over the main rink, which, unlike other rinks in the city’s parks, is not surrounded by any kind of fencing, making the site more porous and open.
The exterior walls are clad in 3 ½ in. thick green Laurentian granite, which is cut by a pneumatically powered guillotine that can create thick chunks of granite quickly and inexpensively.
The central feature of the design is the 5 ft thick canopy, which measures 108 ft wide by 240 ft long and hovers 23 ft above the hockey rink. The initial design called for two deep channels on each side of the canopy and a ceiling manufactured with flat seamed metal. The channels would have had a series of recessed lights that would shine on the ice, which would then reflect it back up to the stainless steel ceiling, creating a glare-free glow.
But this proved too expensive. Instead, TWBTA’s partner Tod Williams became inspired by old instruction sheets with images of the compulsory figures formerly required in the sport of figure skating. This led to a series of curves and arcs carved into the canopy, which was now sided in synthetic stucco, painted midnight blue. Because the incisions for the skating patterns were shallower than the original channels, they no longer needed steel beams; they could be nearly as deep as the canopy itself. The canopy is constructed of open-web joists that span the width of the structure.
The elliptical rink and the hockey rink are connected by a 30 ft wide “ice slab;” when hockey is being played, large dasher gates will close to separate the rinks. Other times, though, the gates will be open, so both rinks can be used for pleasure skating at the same time.
The link has its own set of brine pipes within its slab, separate from the hockey slab and elliptical rink slab. “Technically this was a hidden challenge because we had to make sure that the pinch points in [the] plan would not crack,” Kim notes, “but more importantly that the gaps at those areas between the three zones of refrigeration piping would not create a line of soft or rough ice.”
The rinks will pull double duty as determined by the weather. The canopy-covered hockey rink will serve as a roller skating rink in the summer; the uncovered skating rink will be converted into an outdoor water plaza. One of the challenges was to find the right surface for all purposes. Too smooth and the water feature during the summer might not be safe for kids; too coarse and it wouldn’t be a good surface for ice skating.
According to Scott Hughes, P.E. S.E., M.ASCE, the partner in charge of the project for the New York City-based engineering firm Robert Silman Associates, a spray wash was used after the concrete placement “to bring up the aggregate—so there was some exposed aggregate—so they could get that more nonslip finish, without turning it into a very abrasive surface that would interfere with the ice forming.”
Kim adds that by water-washing the concrete before it was fully cured, additional slip resistance was added. Conversely, because the hockey rink turns into a roller skating rink in summer, the surface of that slab had to be diamond-ground to a smooth polish. “This is a process similar to terrazzo grinding,” says Kim. “As far as I know, Lakeside is the first rink in the world with these two slab finishes.”
Concrete was reinforced more than is typical to keep any cracks that might form from expanding. The engineers used pozzolan, Hughes notes, consisting of such recycled materials as fly ash or blast furnace slag, to replace a portion of the cement paste, to help reduce shrinkage as the concrete cures. Finally, shrinkage-compensating admixtures helped further reduce drying and plastic shrinkage.
The project is pursuing a gold-level certification in the U.S. Green Building Council’s Leadership in Energy and Environmental Engineering (LEED) program. The structures are embedded in the landscape to reduce their visual impact and optimize their thermal efficiency. According to TWBTA, the roof of the canopy is planted with sedum and areas of the roof terrace are planted with shrubs and grasses. Water is collected from the planted areas and recirculated for irrigation. The refrigeration system for the ice rinks utilizes ammonia, which does not contribute to ozone depletion. And heat recovered from refrigeration will be used to preheat the building’s water.