A Respite from the Hot Texas Sun: Rowlett Embraces Cooling Effects of Street Trees

Dallas suburb revitalizes its downtown core, transforming into a transit-oriented development in which street trees planted in Silva Cells play an integral role

Overview

The new blue line DART (Dallas Area Rapid Transit) station opened in Downtown Rowlett in 2012 — and city officials quickly recognized a revitalization opportunity: a mixed-use transit-oriented development providing simple access to the station as well as a diverse array of new community amenities, from modern residential living to exciting new restaurants and breweries. The first phase broke ground in 2014 with the design team at La Terra Studio leading the award-winning development’s landscape architecture component. To offset the concrete-heavy project elements — including widened pedestrian sidewalks and on-street parking — street trees became an important feature: a vibrant urban forest that not only encourages outdoor gathering but provides a shady respite from the hot Texas sun (in addition to other environmental benefits, including carbon sequestration and lowered local energy costs). More than 60 trees (bur oak and Shumard oak) were planted in Silva Cells, their impressive growth performance helping ensure the system’s utilization in the development’s second phase in 2020, where another series of street trees were planted, extending the shady corridor east down Main Street.

Installation Summary

Number of Silva Cells: 1,590 (2x)

Number of Trees: 88

Type of Project: Streetscape, Courtyard, Municipal

Project Designer: La Terra Studio

Project Contractor: Phillips/May Corporation

Installation Date of Silva Cells: 2014 (Phase 1) and 2020 (Phase 2)

The New Downtown Rowlett

The DART station in Downtown Rowlett, providing light rail service to Dallas from the northeastern suburb, officially opened in 2012. Access to public transit had been a decades-long challenge for residents — and the new station presented locals with an opportunity to do more than simply take the blue-line train. “I think this is going to be a great city for people to come to. Not just an origination point, but a destination as well,” observed Gary Thomas, then-president and executive director at DART.

City officials heeded his message. Rowlett’s adjacent downtown core underwent an ambitious revitalization shortly after the station’s opening: the vision was for a mixed-use transit-oriented development that would renew the aging city center. The new $34 million development has a “village” ambiance — which also serves as the unofficial name of the new community. According to the developers, they strove to create “memorable streetscapes and an agrarian-inspired architecture and open space design. The community offers a small town experience by having direct connections to the neighborhood around it, ground level units with front porches and stoops, [and] direct access to the DART light rail station.”

New modern housing, pedestrian amenities, and inviting open spaces were also components of the new Downtown Rowlett. Green space and green infrastructure were also weaved into the design from the outset; as noted in a Rowlett overview of the initiative, “The project has been planned to highlight existing trees and offer a range of green amenities including a community garden, rainwater harvesting, yoga patio, lounge pool and fire pits, pocket parks, and urban streetscapes all in an effort to deliver an urban resort-like experience unique to Rowlett.”

The landscaping element of the project was led by the team at La Terra Studio — who envisioned dozens of new street trees supported by Silva Cells.

Transit-Oriented Developments, Streetscape Trees, and Silva Cells

Transit-oriented developments are an effective way to help lower individual carbon footprints: people are staying in one place — often fulfilling home, professional, and recreational needs in the same community — and, when leaving the area, are more likely than other residents to utilize public transportation than their own car. But increased urban density also inevitably leads to more hardscapes, heat islands, and stormwater runoff. One way to combat this is by prioritizing the growth of healthy, mature trees.

La Terra took this to heart. “The initial investment was for tree health — and we had all convinced the city that this was a great way to invest in these trees on the streetscape: a good technology to grow good trees,” said Brad Moulton, then-project manager at La Terra. Having previously used Silva Cells in the San Jacinto Plaza project (located just across Lake Ray Hubbard from Rowlett), the team was indeed well aware of its tree-growing advantages.

Over 60 trees were planted in the first phase of the project (in 2014), lining a number of streetscapes in the new development. A decade later and the trees have shown impressive growth, helping mitigate the heat island effect for both walking pedestrians and parked cars beneath the trees’ canopies. Indeed, the Silva Cell trees have performed much better than their non-Silva Cell counterparts.

“Silva Cells are a great product that I’ve been involved with since the inception. It’s a great advancement on the typical five-by-five bathtub that an urban tree is [traditionally] relegated to.” – Brad Moulton, Then-Project Manager at La Terra

Access to uncompacted soil is one of the most important factors in the success or failure of an urban tree. This is precisely what Silva Cells provide, in contrast to traditional planting fixtures. As Moulton says, “I always show people the picture of the empty 80-foot-long trench: this is what we’re filling in with soil [within Silva Cells], and you’re getting this amount of root volume versus your typical five-by-five pit. Then when they decide to do the traditional pit, they can’t complain and say ‘Hey, why didn’t these trees last 20 years?’ — I showed you those pictures.”

A study completed of Rowlett’s urban forests in 2018 placed its total value at $310 million, an admirable municipal asset. The report also identified the city’s canopy coverage at 21.5% — and to raise this canopy number by 5%, the report suggested another 20,000 trees would need to be planted. The second phase of the Downtown Rowlett redevelopment (in 2020) is playing its part, picking up where its predecessor left off, also prioritizing trees: “One of the features of the reconstruction project was to continue to add trees along the sidewalks of Main Street. The trees provide both shade and safety for pedestrians walking. Additionally, shade for the sidewalks and streets reduces the temperature of the concrete [and] lessens the heat released overnight.”

The Silva Cell system was also used in this round, supporting another two dozens trees along Main Street, extending east with new developments and corresponding street trees. In addition to providing ideal conditions for tree growth, La Terra Studio also came back to DeepRoot because of their attention to service. “I think the best thing was the collaboration between the engineers and the team at DeepRoot, where we were working on layouts and we could share drawings. That was something that I always appreciated: the coordination and work the internal team could provide, [from] sending CAD files back and forth all the way to installation,” said Moulton.