Trees are valuable assets for any property, regardless of whether it’s private or public property, providing shade, beauty, and environmental benefits. However, trees can also pose challenges when it comes to installing sidewalks, driveways, or other hardscapes near their roots. Tree roots can damage the pavement by lifting, cracking, or buckling it, and pavement can harm the tree by compacting the soil, reducing water and oxygen availability, and injuring the roots.
Fortunately, there are some great alternative tree protection measures that can help you install a sidewalk within close proximity to the trunk of a tree without compromising its health or stability. In this blog post, we will discuss three of these measures: permeable concrete, decomposed granite, and root bridging.
PERMEABLE CONCRETE
Permeable concrete is a special type of concrete that has a high porosity, allowing water and air to pass through it. This reduces the runoff from the pavement and allows the water to infiltrate the soil and reach the tree roots. Permeable concrete also prevents soil compaction and maintains the natural temperature and moisture conditions of the soil. Permeable concrete can be used for sidewalks, parking lots, patios, and other flatwork applications.
To install permeable concrete, you need to prepare the subgrade by removing any organic matter, leveling the surface, and compacting the soil. Then, you need to place a layer of crushed stone or gravel as a base, followed by a layer of permeable concrete. The concrete mix should consist of cement, coarse aggregate, water, and admixtures, with little to no fine aggregate. The concrete should be placed, screeded, and finished with a roller or a broom, leaving a rough texture to increase the permeability. The concrete should be cured for at least seven days, keeping it moist and protected from traffic.
Decomposed Granite
Decomposed granite can be a great alternative to concrete when installing a sidewalk or pedestrian right of way in close proximity to a tree’s trunk and critical root zone.
Decomposed granite is a natural material that consists of small particles of weathered and eroded granite. Decomposed granite has a sandy or gravel-like texture and comes in various colors, such as tan, brown, gray, red, or green. Decomposed granite can be used as a mulch, a paving material, or a filler between pavers or flagstones. Decomposed granite is permeable, durable, and aesthetically pleasing.
If you want to add more stability and durability, as well as prevent future maintenance to your decomposed granite, you can also apply a chemical stabilizer to the surface. A chemical stabilizer is a liquid product that binds the decomposed granite particles together and forms a solid layer that resists erosion, cracking, and shifting. Some examples of chemical stabilizers are Organic-Lock, Stabilizer Solutions, and TechniSoil G3 Pathway Stabilizer. These products are environmentally friendly, easy to use, and maintain the permeability of the decomposed granite.
To apply a chemical stabilizer, you need to follow the instructions of the product you choose, but generally, the steps are as follows:
– Mix the stabilizer with water in a ratio recommended by the manufacturer.
– Spray the stabilizer solution evenly over the decomposed granite surface, using a garden sprayer or a hose-end sprayer.
– Allow the stabilizer to penetrate and dry for at least 24 hours, keeping the surface moist and protected from traffic.
Root Bridging
Root bridging is a technique that involves creating a raised platform over the tree roots, leaving a gap between the pavement and the soil. This allows the tree roots to grow freely under the platform, without being damaged or disturbed by the pavement. Root bridging also preserves the soil structure and moisture, and reduces the risk of root rot or fungal infections. Root bridging can be done with metal, wood, or other materials, depending on the site conditions and the design preferences.
To install root bridging, you need to identify the tree roots that are causing or may cause pavement damage. Then, you need to place metal or wooden beams or planks over the roots, parallel to the sidewalk direction, and secure them with stakes or anchors. The beams or planks should be spaced at least six inches apart, and the gap between the pavement and the soil should be at least four inches. Next, you need to place metal or wooden decking or panels over the beams or planks, perpendicular to the sidewalk direction, and fasten them with screws or nails. The decking or panels should be flush with the existing pavement level, and have drainage holes or gaps to allow water to pass through. Finally, you need to fill the gap between the pavement and the soil with mulch, gravel, or sand, to prevent soil erosion and weed growth.
IN CONCLUSION,
Just because you’re starting a construction project just because you’re starting a construction project around mature, send me mature, or heritage trees, does not mean that the trees need to be removed or suffer from construction damage more than the tree can handle. By applying any of these three alternative tree preservation measures, trees can easily be saved, thereby improving the community as a whole and even your personal property.
For more information or if you need help keeping your trees healthy and thriving throughout construction, please feel free to reach out to us at www.arboristondemand.org, or reach out to us by phone at 409.995.7940
Hope this helps, and thank you for taking the time to check out this cool article 🙂
My Best,
Matt Latham – 409.995.7940
ISA Board Certified Master Arborist #TX-3737B
mattlathambcma@gmail.com