Centennial Park Texas Case Study - 5 Years Later

Project Challenges

Designing Centennial Park came with several key challenges that had to be addressed to ensure the trees would not just survive, but thrive:

Poor soil conditions: The existing ground was heavily compacted and lacked nutrients, unable to support robust root growth. This is a common issue in city centers, where construction and decades of use leave soil in bad condition (essentially “dirt” with little organic content). Without intervention, tree roots would have insufficient space and nutrition.

Harsh west Texas climate: Midland’s climate is hot and semi-arid. Drought and high summer temperatures put trees under stress, and irrigation would be necessary to establish and maintain any new plantings. The landscape needed to incorporate water management for the trees in a sustainable way, especially given the region’s limited rainfall.

Impervious surfaces & urban infrastructure: The park design included paved promenades and plaza areas, meaning much of the tree root zone would lie beneath hardscape. Creating adequate soil volume under sidewalks and plazas (without causing pavement to heave as roots grow) was a challenge. Additionally, the downtown site had underground utilities and even retaining wall structures from surrounding features, which complicated excavation and planting locations. The tree planting system had to be flexible enough to work around these constraints.

Solution & Design Approach

To overcome the urban limitations, the design team turned to Citygreen’s Stratavault as their preferred structural soil cell system. This modular soil cell technology provided a way to create large volumes of quality soil underground while still supporting the weight of pavement above. In total, approximately 50,000 cubic feet of soil was allocated for the park’s trees using the Stratavault system.

The Stratavault units form a skeletal matrix that holds soil in an uncompacted state (ideal for root growth) beneath the hardscape. It replaces what would have been dense, load bearing subgrade with a soil filled matrix that can support sidewalks but also serve as fertile rooting space.

Crucially, the landscape architects designed a network of linear connected tree pits rather than isolated planting holes. By connecting multiple tree planting zones into continuous soil trenches, the root systems of neighboring trees can eventually intermingle and share resources in one large soil volume. This approach means each tree effectively has access to more soil than if it were in a small separate pit, enabling it to grow to full maturity. Beneficially, it also reduced the total soil volume needed per tree, improving cost efficiency.

Cost was a consideration, so the team looked for ways to use site resources wisely. Instead of sourcing all new soil, they re-used much of the excavated native soil to fill the Stratavault cells, after enhancing it with organic matter and nutrients. By amending and reusing the existing soil on site, the project saved on hauling in many truckloads of specialized soil mix. The excavated soil was used both inside the cells (around the tree root balls) and to backfill above and around the structured cell matrix once installation was complete. This sustainable practice not only cut costs but also reduced waste and construction traffic in the downtown area.

Water management for the trees was addressed through design as well. Even drought tolerant species benefit from irrigation when establishing roots, so an efficient drip irrigation network was installed above the soil cell matrix to deliver water directly to the tree roots as needed. Uniquely, Centennial Park’s irrigation is fed by a reclaimed water system: an underground rainwater harvesting cistern (using R-Tank® modules) captures and stores stormwater, which is then used to water the trees and landscaping. This closed-loop system reduces reliance on city water and helps the trees survive Midland’s dry spells by making the most of the rainfall the site receives. It’s an elegant example of Low Impact Development (LID) strategies, pairing well with the soil cell solution to deliver healthy trees and sustainable stormwater use in one solution.

Five years on, Centennial Park’s trees are stunning examples of healthy trees, validating the planning and technology that went into their planting. The once-barren plaza is now lined with a growing canopy of healthy trees, providing much-needed shade over pathways and seating areas. In this 2025 photo, lush green lawns and mature tree crowns frame the park’s splash pad and pavilion – a stark contrast to the construction site of 2019. The Stratavault system beneath the surface has done its job, allowing roots to spread extensively and securely below the busy promenades. Visitors can stroll under the dappled shade even on hot summer days, enjoying a cooler micro-climate created by the trees’ transpiration and cover.

The success of Centennial Park’s greenery is perhaps best measured by the experience it offers the community. What was once an uninviting concrete expanse is now a vibrant gathering spot in downtown Midland. The park sees daily use by families, downtown employees, and tourists alike – whether it’s children climbing on the playground logs, people relaxing under the oaks, or crowds assembling for concerts and festivals on the great lawn. In fact, the park has become Midland’s central civic space, hosting events from movie nights to holiday celebrations. The transformation has been so effective that the project earned a Texas ASLA Award of Honor in 2023 for its sustainable design, which

highlighted features like the sub-surface soil cell system enabling a thriving new tree canopy and the integration of rainwater harvesting for irrigation. From a tree-growth perspective, the outcomes are
impressive. The trees planted in 2019 have established strong root systems and are well on their way to achieving a full, mature canopy well before they normally would in harsh urban conditions. Leaf surface area and shade coverage have expanded dramatically – fulfilling the design goal of increasing shaded public space by a factor of 2–3 times over the former plaza’s state. The robust root environment means these trees are healthier, more resistant to drought, and will likely live decades longer than the nearby street trees planted in conventional pits.

Inspiration for Future Projects

Centennial Park’s story shows how thinking outside the box (and under the pavement) can solve the classic challenges of urban tree planting. By addressing soil volume, quality, and water supply
through technical innovation, a city that once struggled to grow downtown trees now enjoys a flourishing urban forest in its central park.

The combination of engineered solutions and creative design turned a difficult site into a beloved green oasis. The success of Midland’s Centennial Park underscores an exciting truth: when we invest in proper green infrastructure for cities, the returns – cooler, healthier, more vibrant public spaces – are well worth the investment.