Guilds Lofts Courtyard—The Yards of DC: Silva Cell Case Study

– Silva Cells help deliver on-site stormwater management that integrates water, soil, and tree roots through bioretention.

– Eight trees each have 800 ft3 of soil and manage 1,600 gallons of stormwater at The Guild Lofts with 282 2X Silva Cells.

– Water is captured on-site from the roof to the ground. The plaza where the trees live is above the parking garage, making it even more necessary for the trees to have supplemental soil volume to thrive.

– DeepRoot helps to advance green infrastructure growth throughout the Yards region.

The Guild Lofts at 1346 4th St. SE in “The Yards” are just steps away from the Anacostia River in Washington, D.C. The Yards is a portion of Washington’s fastest-growing, 500-acre neighborhood, Capitol Riverfront, and it’s growing with resilient urban infrastructure.

The Guild has 191 residential units in addition to retail and restaurants, just adjacent to the historic Navy Yards district. The Guild Lofts also houses an underground parking garage, just below the courtyard where eight trees were planted to provide shade for a mixed-use area with benches and five, red, modular sculptures by Artemis Herber. When DeepRoot’s longtime design partner, ParkerRodriquez, were planning the courtyard they specified 282 2X Silva Cells, allowing the team to accomplish the following goals and requirements:

  • Maximizing soil volume for eight trees over the garage structure and still maintaining a usable surface
  • Retaining and managing 1,600 gallons of stormwater on-site
  • Complying with the Department of Energy and Environment’s Green Area Ratio (GAR) requirement

Honey Locusts (gleditsia triacanthos), permeable pavement, and simple benches provide shade and color in the courtyard at the Guild Lofts in The Yards. Photo courtesy of The Guild Lofts.

Eight vibrant Honey Locusts (gleditsia triacanthos) were planted in Silva Cells in December 2018, each receiving an average of 800 ft3 of soil volume.  The trees are commonly found in the central United States, near moist soil in river valleys. To give the trees the foundation and soil support they need to grow healthy and strong, and meet the goals set by ParkerRodriquez, soil volume was top of mind. ParkerRodriquez has successfully used Silva Cells several times before and knew they would be key in creating a project that looked good for decades, not just months or years.

 “We have used Silva Cells on several other projects, but at The Yards it gave us the chance to utilize the full capacity of the Silva Cell system by integrating stormwater. This enabled us to meet the new GAR standards while providing the soil volume needs of the trees to develop into a full and beautiful canopy that helps to mitigate the Urban Heat Island effect and improve climate resiliency.”—Steven M. Sattler, PLA, ParkerRodriquez

Ruppert Landscape installing Silva Cells in December 2018.

Integrating and Managing Water and Soil

 Installing Silva Cells in this project optimized and prioritized tree health for the long run and met stormwater management goals and environmental regulation compliance. The Silva Cells provide underground bioretention, managing thousands of gallons of stormwater on-site. The pavers are permeable, helping to mitigate flood concerns. The pavers and the Silva Cells combined with the trees themselves, all contribute to satisfying the GAR requirement. The GAR is an environmental sustainability zoning regulation that sets standards for landscape and site design. It helps to reduce stormwater runoff, improve air quality, and prevent sediment pollution from entering the Anacostia River.

On the building rooftop, collection pipes were installed and connected to a down drain, along with a green roof to reduce the peak rates of runoff. During a storm, the water travels into a distribution pipe that is installed at the top of the Silva Cell system. The water-loving Honey Locusts will benefit from this abundance of water, so during the hot summer months the transpiration process will naturally lower the air temperature, creating cooling in the immediate courtyard area. This is a critical strategy in reducing the Urban Heat Island Effect, providing a key climate change mitigation component.

Drawing from ParkerRodriquez of Silva Cells

The State of Green Infrastructure Throughout the Capital

Two years in and the Guild Lofts courtyard Honey Locusts have shown great progress. But how is the rest of the fastest-growing neighborhood of D.C. doing when it comes to adding green infrastructure? Our friends over at Casey Trees have mapped out the D.C. region’s tree canopy, specifically looking at street trees. Zoomed in, we can see that The Yards region is underrepresented in greenery. DeepRoot is excited to be a conduit that helps urban trees thrive with Silva Cells and especially pleased to know that our product will help make trees last in areas that have far fewer plantings, to begin with. For DeepRoot, helping remedy the lack of greenery in the area also means an opportunity to contribute to social equality.

Screenshot of Casey Map D.C. street trees A screenshot from Casey Trees’ street treemap shows the lack of trees in the Yards region. The orange color indicates other DeepRoot projects; the red is the Guild Lofts project.

We can’t wait to see how the trees at The Guild Lofts grow in another two years!

Installation Summary
Number of Silva Cells: 282 2X
Amount of soil volume and stormwater management: Per tree average—800 ft3
& 1,600 gallons of stormwater captured on-site
Number of trees and type: 8 Honey Locust trees
Type of project: Integrated trees, housing, urban, stormwater, plaza, courtyard
Project designer: ParkerRodriquez
Project contractor: Ruppert Landscape
Installation date of Silva Cells: December 2018
Project timeline: 2018–2019