A sustainable oasis in St.Louis

The majestic Gateway Arch National Park in St.Louis, Missouri, just celebrated the first anniversary of its renovation.

by Anna Volpicelli
6 min read
by Anna Volpicelli
6 min read

Designed by the American-Finnish architect, Eero Saarinen, the monument was originally dedicated to Thomas Jefferson to honor his ideas for America’swestward expansion. For more than 50 years, the renowned arched structure has been cut off from the rest of the city. That is, until Brooklyn-based landscape firm Michael Van Valkenburg Associates, Inc. (MVVA) transformed the surrounding area into a sustainable green oasis where people could mingle and enjoy the view of the Mississippi River.

A lesson in resilience and sustainability

After five years of work, the Gateway Arch National Park reopened on July 3, 2018. Among its many changes was the expansion of Luther Ely Smith Square, a grassy land bridge over I-44 that connects the park grounds and downtown, and the city’s Old Courthouse and newly redesigned Kiener Plaza. Before the renovation work began, one of the priorities of the landscape architecture firm was to develop a project that was accessible, environmentally-friendly, aesthetically beautiful and that could ease the connection between people and the Gateway Arch National Park.
“Our focus was on sustainability and resilience,” explained Gullivar Shepard, MVVA’s lead design principal on the project. “We worked on different areas, from the soil to the underground garage, to achieve this goal.”

A new green oasis

The investment on the redesign was about $380 million, which was financed with public and private funding. One of the most significant parts of the restylingwas the removal of the parking garage that was originally located at the North Gateway.
“We wanted to break the barrier between local communities and the isolation of this national monument and create an area where people could mingle and interact in a healthy way,” said Shepard. “Destroying the parking lot was a huge part of that because it opened up roadways [that served as] a new connection between the buildings and people.”

The area is now a natural amphitheater with 7.5 acres of green space with a pollinator garden and 3 acres of native prairie. A new eco-oasis is responsible for carbon sequestration, a process in which carbon dioxide is removed from the atmosphere and stored in the soil. According to National Park Service data, the area sequesters approximately 55,000 pounds of carbon annually.

Water savings

Not only did the destruction of the parking garage in the North Gateway improve air quality, it also reduced the amount of toxic runoff in the area, which affected the quality of the water in the Mississippi River. The installation of disrupting sustainable stormwater structures also played a significant environmental role. MVVA designed a new irrigation system that boasts vast efficiency—it can shut off on its own if the ground is wet from rainfall. It also includes two underground retention tanks. The 37,000-gallon retention tanks, one at The North Gateway and the other one at Luther Ely Smith Square, separate silt and excess nutrients before releasing the water. The tanks successfully filter out sediment and nutrients from the water, which is then reused in the irrigation system.

Rooted in a healthy foundation

Aware of the importance of a healthy landscape in public spaces, the Brooklyn-based firm also planned for a complete soil reconstruction around in the North Gateway and Luther Ely Smith Square. “We had to remove 900 ash trees prone to infestation by the Emerald Ash Borer that were very old and not healthy at all,” explained Luke Ness, MVVA senior associate. “We replaced them with London plane trees, which are stronger and healthier.”
In addition, 35,605 gallons of liquid biological amendment, an organic tea made from compost, were added to the soil to increase microbial activity and promote the growth of trees, bushes and flowers of the park.
“We also had 130,000 cubic yards of soil brought into the site,” Ness continued, explaining that such details help keep oxygen [production] alive. The inspiration to restore the landscape came from agricultural practices that focused on the elimination of chemicals and fertilizers. “We talked to biologists and experts in the field to design a perfect soil blend that could make a long-term impact,” said Ness. The blend combines different types of soil, such as sub-soil, tree, bioswale and structural soils, which help reduce compaction and runoff while allowing for absorption and promoting root growth. Oilseed radishes were also planted. “These open up these giant holes, and then they decompose, leaving organic matter and airspace so you have more water and nutrients for the land,” said Shepard.


Award recognition

The renovation included the landscape around the Gateway Arch, as well as the underground visitor center and museum. Designed by the New York-based design firm Cooper Robertson and James Carpenter Design Associates, in collaboration with the St. Louis-based Trivers Associates, the new areas were just awarded LEED Gold certification. The restyle of this art adobe touched all the galleries, public amenities and educational facilities, and added an area of 47,000 square fee, which includes a 3.1-acre green roof. More than 98% of the interiors are covered by vegetation, which helps reduce the heat island effect, and the higher level of thermal efficiency work to reduce the consumption of energy.
The firm included in its renovations a series of low-flow water fixtures that can reduce the use of potable water. Data shows that the energy cost savings for the project are around 24% below the baseline, and potable water usage is reduced by more than 31%.