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StormTree designs two types of tree “systems”: (1) “tree filters” which are designed and sized to meet regulatory compliance for nutrient (pollutant) removal as a stormwater management system, while providing healthy tree growth; (2) “tree pits” that are not intended to meet regulatory standards; are designed primarily to support healthy, vigorous tree growth in a heavily impervious environment.

What’s the difference between tree filters and tree pits?

Our systems do not require structural cells or separate external infrastructure support systems to support pavement or prevent soil compaction.

Do StormTree systems require proprietary “structural cells” or other infrastructure to prevent soil compaction and suspend and support pavement?

No. Our systems do not require, and we do not recommend the use of structural soils in close proximity to our systems. Our recommended soil blends and “recipes” are based on readily obtainable soil, organics, and aggregates.

Do StormTree systems require the use of “structural soil” or other proprietary stone-base soils in their systems?

Absolutely not! StormTree systems are not closed “boxes”. The unique open sided and open bottom design allows for unrestricted tree root development and healthier tree growth.  As we like to say, “we don’t box the tree, we frame the tree”.

What about the tree? Is this one of those closed box “tree coffins”?

For our tree filter systems for regulatory stormwater management, we maintain a list of trees suitable for various regions throughout the U.S. and Canada. Recommended trees typically attain a height of less than 30 feet. We will also consider suggested alternate species.


Our tree pit systems for heavily impervious environments can be installed with any typical street tree without height restriction.

What type of tree can we use?

Based on StormTree’s open design, correct installation and proper care and maintenance practices, the tree will probably outlive you.

How long will the tree last?

As designed, the planting depth of the trees in a StormTree system is several inches below the sidewalk surface and are directed further downward and outward. The soil media used is highly porous and oxygen rich, discouraging roots from seeking porous base soils just below sidewalks.

As the tree matures, will its roots eventually cause sidewalk upheaval or lifting?

Possibly.  If systems are to serve primarily as tree pits for healthy and vigorous growth, and subsurface soils are known to infiltrate naturally preventing waterlogging, then underdrain pipes may not be necessary.

Can StormTree systems be installed without underdrain pipes?

Yes, provided it meets the specific criteria for your project, and is recognized to support healthy tree growth based on industry standards.

Can I specify my own soil mix or “recipe” for your systems?

We provide complete and comprehensive construction details and operation and maintenance guidelines, as well as virtual response and support as requested.

How do you ensure proper contractor installation of your systems?

Typically, we use ADA (American Disability Act) compliant fiberglass grating, however, any manufactured metal or plastic tree grates are suitable.

What type of grate can be used with these systems?

Yes, provided that it meets the definition of a “tree grate” and is customarily used as such.

Can an engineer or landscape designer specify a particular style and dimension of grate?

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