New York City is certainly willing to pay top dollar for excellent design. A new $3 billion water treatment plant is taking shape in Van Cortlandt park in the Bronx. The Croton water treatment by Grimshaw Architects and Ken Smith Landscape Architects includes some $250 million in new buildings, plazas, wetlands and meadows, and a public golf driving range, which, amazingly, sits right on top of the plant. In a session at the 2012 ASLA Annual Meeting in Phoenix, Ken Smith, ASLA, Ken Smith Landscape Architects; David Burke, Grimshaw Architects; and Charles McKinney, Affiliate ASLA, City of New York, Department of Parks and Recreation, explained how the project is the result of NYC's design, stormwater management, and parks policies. And while these numerous policies and design requirements were sometimes in conflict, said Smith, the design eventually succeeded because it cleverly integrated security and stormwater management features with public amenities.

McKinney explained that NYC's government under Mayor Bloomberg has been consistently encouraging practices that create great design, but by necessity, not just out of big city ego. Mayor Bloomberg believes that design excellence yields better results, improves property values, and strengthens investor confidence. In reality, though, it's about being able to pay the money required to achieve a range of goals, in the area of climate change, public parks, and stormwater management. Under Bloomberg's PlaNYC, all of the city's commissioners had to come up with new ways of doing things to accommodate the expected one million people that will move into the city over the next 20 years while also preparing for climate change. For the parks department, this meant holding themselves to the new goal of having every citizen within a 10 minute walk of a park and creating major new parks. An off-shoot of PlaNYC that also relates to the city's parks is NYC's bold green infrastructure plan, which helps the city achieve its new goals related to managing stormwater. The new multi-billion dollar green infrastructure plan is expected to decrease the amount of overflow rainwater that overcomes the city's old combined sewer system by billions of gallons.

McKinney explained how other NYC initiatives boost performance in different realms: the Active Design Guidelines combat obesity, the Street Design Guidelines encourage new forms of mobility, the High Performance Infrastructure Guidelines help create greener infrastructure systems, the High Performance Landscape Guidelines will help ensure the city's parks are greener, and the Department of Design and Construction's Design Excellence Program means projects will be selected on merit and quality instead of price. McKinney said through these programs "all city residents have benefited." And in the case of the the Croton project, the design result is even "transcendent."

NYC's water conveyance system is as crucial to making the city what it is today as the elevator, said Smith, quoting Norval White's book, New York: A Physical History. Together, the water system and elevators enabled NYC's density. And while the grid was laid out in 1812, the water system from the 19th century really made the city work. Before, Smith said, there were "private water systems, primitive distribution systems."

The Croton water treatment plant was built because of fears about the city's water quality. The Croton watershed had been jeopardy due to naturally-occurring compounds, said Burke. After reviewing 14 possible sites, the city found that a spot in Van Cortlandt park would actually be the most cost-effective. After the city dithered on moving forward with the Bronx site, the federal government issued a mandate saying the facility had to be built. The federal government also said that while aspects of the park had to be uprooted during construction, all pieces had to be replaced after the plant went in. That meant eventually restoring the original golf course driving range found there.

The 9-acre-square plant is set below ground, up to 100 feet deep in some spots. Driving through sheer bedrock, the complex plant being created by infrastructure engineers will help the city purify the huge amount of water it uses daily, about 1.23 million gallons. Smith, the landscape architect designing all the landscape elements, said the roof of the plant was now in place, creating the largest green roof in the country.

Smith and Burke walked the crowd through the many challenges in knitting the design together while addressing all of NYC's issues. One entrance to the facility needs to be highly secure, with space for car and truck X-ray machines, while other access points need to be easy, public. There had to be room for a chemical discharge station, which is used to funnel the chemicals needed to clean the water. All stormwater had to be captured on site, so there had to be a careful analysis of the terrain and existing riparian woodlots. The site also needed to channel or produce water for the golf range and native meadows and wetlands.

Smith outlined how an ingenious system of water conveyance was created that leveraged existing water flows. New bioswales and natural treatment systems were put in to help retain water and also channel it to a man-made lake. The NYC government said the project really had to be more of a landscape project than a building one so artistic integration of the buildings into the landscape was also a key issue. Burke, an architect, said "we had to blur the lines between landscape and building," which for him was a learning experience.

Multiple schemes were batted around before everyone settled on a circular design that provides multiple benefits, said Smith. The round shape not only provides some coherence for the golf course but also obscured a reading of the invaluable plant underneath. Like the layers in a onion, the design provides 2-miles of gabioned, stone-clad, and core-ten steel walls in rings at different heights, each providing different functions. To block vehicular traffic, there are 3-feet high walls, while intruders on foot will be stopped by 10-feet sheer walls. Smith said the site design uses a moat, "a primitive military mechanism," to solve contemporary challenges. The moat itself is filled with bioretention systems but really it's there to enable dramatic grade shifts so the walls don't seem too intrusive.

McKinney stepped in to add that the original design, well, wasn't really a design at all, but an "engineering solution," offering a big box in a park, which was "not a good thing." Now, the design is a "landscape. This is the breakthrough."

The public golf driving range also works with the moat. Golfers will send their ball out over the moat, while the roof itself will use a "Xmas tree" formation of targets to enable golfers at different skill levels to enjoy.

The green roof itself is inaccessible to the public. Smith said months of research went into making the sub-structures, which consist of many layers, work. Grades had to be carefully thought out, too, to ensure maintenance vehicles and ball collectors could get on the roof. Eventually, a bowl shaped was settled on for the course for aesthetic and technical reasons. Smith, who's known for his deep appreciation of materials, described his examination of all the different foams, natural and artificial turfs, and soils he and the golf consultants tested at great length.

McKinney, Burke, and Smith all described lessons learned from the project. For Burke, the lead on the project, the learning curve working with such an interdisciplinary team was steep. Solving multiple challenges in a collaborative environment was new. "We worked with many consultant we don't usually work with and had to learn their language." Smith said working with some "retrograde engineers" who were part of the original team was a real problem, as they didn't understand why a design team was coming in to design the stormwater management systems and green roof. He said infrastructural engineers are excellent at what they do, but "public space design is not in their skill set."

One audience member seemed to wonder why this landscape architecture project was led by an architect, David Burke at Grimshaw, instead of the landscape architect, Ken Smith. Little known fact: under NYC's design excellence program rules, projects like these can't be led by a landscape architect. This is one of the only instances where this is the case among design excellence programs. Hopefully, as the central work of Smith on this project demonstrates, interdisciplinary projects can just as easily be led by a landscape architect as an architect. In fact, Burke seemed to say as much when he said it didn't really matter who was the lead or sub-contractor in this effort, the effort was a deep collaboration between architect and landscape architect. Let's hope the city starts to understand this, too.

Explore the project in depth.

Image credits: Grimshaw Architects and Ken Smith Workshop