The Bullitt Center site was chosen for its relationship to ... · To protect the trees the design needed to be surgical in the modifications for both the hardscape and softscape

Bullitt Center & McGilvra Park - 1

The Bullitt Center site was chosen for its relationship to adjacent green space, McGilvra Place Park, and a walk score of nearly 100. Its urban context made it the first building of its kind to pursue Living Building Challenge (LBC).


The private development project, underutilized public green space, and street between the two created a great opportunity for a public-private partnership. This site plan also highlights the water flow of each site.


To achieve LBC required a performance-driven design approach. Everything needed to have multiple reasons for being.


Rooftop rainwater is collected and used in the building for potable uses. Greywater flows to constructed wetlands to be treated and infiltrated through planters at grade. Stormwater flows to the rain garden. Permeable grating allows both function and access.


Detail view of 15th Avenue’s curbless streetscape where a greywater planter, bench, grating, and trench drain bypass toward the rain garden and various planting typologies, all visible to the public.


Plantings on 15th Avenue cleanse and filter the site’s greywater and stormwater. Species selected for the rain garden and infiltration planter tolerate wide fluctuations in moisture levels. The palette was chosen to make its functions visually intuitive to the public.


Existing trees thrived despite tough urban conditions. They inspired the team and drove many design decisions. Roots were carefully excavated with an air spade to ensure they were not damaged. They were given more access to air and water.


Existing concrete sidewalks crowding the trees were salvaged for reuse. The concrete was sawcut into new large- and small-scale modules and reinstalled onsite to serve as pavers and stair treads.


The design preserved the existing raised concrete planter walls but strategically removed two sections enabling barrier-free access into center of the tree canopy. Removed sections were retained onsite as remnants and reinforce the concept of material salvage and reuse.


Curbless space is open to only non-motorized uses aside from emergency vehicles. New hardscape and grading required surgical insertion between existing trees. Every piece of existing hardscape in park was salvaged and reused onsite.


The design replaced highly consumptive irrigated lawn with drought-tolerant plants. Student Conservation Association (SCA), along with clients, community and design team members installed all the plants in the park.


Trees inspired the design team to show how precious they are to the urban realm and design shows wood in many forms. Furthest from building: raw form. Closest to building: most crafted. Heavy timber structure is visible from outside.


The transformation of McGilvra Place Park from an underused right-of-way to a pedestrian and bike-friendly activated space was supported by surrounding neighborhood plans, City of Seattle Comprehensive Plan, and goals of the stakeholders.


Park renovations came from a community-led application to improve accessibility and demonstrate innovative stormwater strategies. Funding came from Seattle Parks Department Opportunity Fund identifying this project as a unique opportunity to improve the site as a public amenity.


The project is a model for private sector and public agencies transforming an underutilized urban street and open space into a dynamic neighborhood gathering space where the latest innovations in ecologically sensitive urban design are made visible to the public.

Bullitt Center and McGilvra Place Park

The Bullitt Center is heralded as the first commercial building in the world to meet the Living Building Challenge (LBC). To meet LBC standards seven performance areas, also known as petals, must demonstrate performance. The landscape contributed to all seven petals—the two most significant being Water and Beauty + Inspiration.

Water

The Water Petal, which requires Net Zero Water and Ecological Water Flow, proved to be one of the most difficult challenges. Engineers and landscape architects created an innovative water system that loops rainwater catchment and wastewater disposal into onsite constructed wetlands and rain gardens to store, purify and recharge water to the landscape.

To achieve Net Zero Water, a Living Building must collect all the water the building needs, including potable drinking water. Ecological Water Flow involves treatment and disposal of all greywater onsite, restoring the site’s ecological processes as close as possible to pre-industrial conditions, in this case a Douglas fir forest. Through a 56,000-gallon rainwater cistern and green infrastructure, the Bullitt Center’s water system returns 61% of the water that falls onsite. No black or grey water is piped to the city sewer.

Composting toilets, sink water and showers use rainwater collected from the solar array and roof surfaces. Greywater temporarily stored in a secondary, gravity fed cistern in the basement is pumped to a constructed wetland and high-performance green roof located on the third floor. The 475-square-foot roof landscape filters 400 gallons of greywater each day. Water recirculates every half hour until it passes through the system four times, allowing the roof to absorb nutrients while cleansing the water to acceptable levels to be returned to the groundwater.

Greywater not lost through evapotranspiration and absorption flows by gravity to an infiltration planter in the public right-of-way adjacent to the west side of the building. A small portion of the site held the characteristics needed to install 40-foot-deep bore trenches to infiltrate the rest of the site’s greywater. As a result, a portion of the infiltration planter is integrated with the main public entrance to the building. A steel grate provides necessary air circulation without exposing the public to greywater. The nearby rain garden, adjacent to and just south of the infiltration planter, processes rainwater that sheet flows from the sidewalk to avoid overloading the infiltration planter.

Beauty + Inspiration

This petal challenges the project to connect site users with their surroundings through history, materials and context. As with the material selections for the building, each plant material in the landscape was required to perform functional benefits as well as reveal the natural processes at work.

The project’s plant palette provides a softened foreground to the building structure while working hard to cleanse and manage stormwater, thrive in the urban environment, and express how urban ecology is integral to supporting the building’s systems. A native plant palette bridges the functional benefits for the landscape while recalling the site’s original landscape.

McGilvra Place Park, located immediately adjacent to the Bullitt Center, is the first to meet the Living Building Challenge for landscape and infrastructure typology. The project activates and enlivens an underutilized streetscape and pocket park in an area specifically identified for more green space in neighborhood plans. Located on a triangular piece of land too small for development, the park consists of a raised planting area and 11 century-old sycamore trees. The land is owned by the Seattle Department of Transportation and maintained by Seattle Parks and Recreation. As a partner in design, the Bullitt Foundation advanced a new model of public-private partnership, helping to leverage private development for public benefit. Through collaboration between Seattle Parks and Recreation, Seattle Department of Transportation and the Bullitt Foundation, the entities will share maintenance responsibilities.

Protecting Trees

Early on, it was clear the priority must be to protect the trees that have thrived for a hundred years and are expected to live for another hundred. The trees showcase our natural environment and provide important ecosystem services by sequestering an estimated 3,200 pounds of carbon each year, approximately half the annual amount of carbon generated by the average driver using a 25-mile-per-gallon vehicle. The trees also intercept approximately 44,000 gallons of water each year, the equivalent of half the average yearly water use for a family of four, almost enough to fill the cistern in the basement of the Bullitt Center.

The Bullitt Center is described as functioning in many of the same ways as a tree, with its photovoltaic canopy, hardworking building core and self-sufficient base managing all of the water and nutrients that move in and out. The juxtaposition of this building and park was a powerful image that inspired many decisions for the park design.

Purposeful Changes

To protect the trees the design needed to be surgical in the modifications for both the hardscape and softscape. The roots extend below the raised planting area, sidewalks and 15th Avenue roadway, where the project called for removing the existing road to create a pedestrian plaza. Disturbing the roots would jeopardize the health of the trees.

As a solution, the site’s existing subgrade was used to locate new park elements. For example, by closing 15th Avenue to vehicles and removing the eastern curb, the park’s deepest new feature, a surface water runnel, was placed in the depression formerly occupied by the curb base without requiring excavation. A new walkway slices through the raised lawn area and thin metal walls retain soil and form stairs, displacing a minimal amount of soil and disturbing the roots as little as possible.

All changes were purposeful, each element contributing to the surrounding environment, whether to slow the progression of water or enhance the ecology and habitat for pollinators and small mammals.

Bike racks, benches made from salvaged local trees and a ping-pong table activate the space and offer more reasons to linger.

Materials Sourcing

The LBC requires products to be made without toxic chemicals and from local sources. The LBC “red list” determines which materials are prohibited. Many common construction products, from posts that support tree protection fencing to aggregates in concrete mixes, are manufactured and shipped from halfway around the world, beyond the limits of local sourcing. As a result, reuse played a big part. While many basic construction materials are on the red list if purchased new, the LBC allows reuse of materials already on hand or available from a previous project. For example, the park contractor used tree protection fence posts from a previous job, and concrete formwork was salvaged from other job sites, as well as some of the erosion-control materials.

To limit the disposal of existing materials from the site, the concrete sidewalk was saw-cut into large-scale pavers and reset as new pathways in the park. The project also revealed that many common finished materials can be eliminated through creative design. For example, raw steel was chosen to avoid high levels of zinc created through processes like galvanization.

Through investment and hard work, both projects push the boundaries of acceptable conventions and offer access to replicable strategies, red listed materials, and real time statistics to rapidly advance the design and governing laws for building truly sustainable structures and open spaces.

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The Bullitt Center site was chosen for its relationship to ... · To protect the trees the design needed to be surgical in the modifications for both the hardscape and softscape