Structural Soil for Urban Trees

Structural Soil for Urban Trees

Currently most urban trees are planted directly into existing compacted urban soil or tree pits with limited root space. Trees that are planted in areas surrounded by paving tend to struggle for air space and usually decline well before they should. Where soil volume is limited by pavement, tree roots suffer and tend to take the path of least resistance searching for air, usually in and around pipes, foundations, or to the surface. Healthy trees need a large volume of non-compacted soil with adequate drainage and aeration and reasonable fertility.structural-soil-expanded-view

While the need and desire for large trees in the urban landscape still is the desired intent, the trees do not survive long enough to fill the need. Not planning for root growth is ignoring the biological requirements of trees and is not economical or environmentally prudent. The failure to provide adequate soil for both drainage and root growth is critical to the life of the tree and without an engineered soil specific to this application, trees have a shortened life span and may die. Ensuring a good supply of air to the tree roots is essential for satisfactory tree growth, however in urban situations, the movement of air into the soil is often restricted. By providing additional root space below the pavement in what otherwise was compacted urban soil, Structural Soil can allow most newly planted trees to have a chance for healthy growth. This mix consists of 80% 75 mm angular clear aggregate  and 20%  approved sandy clay loam. The aggregates bear the load, providing the structural stability for the pavement above. The angularity of the rock create for the non-compacted soil, providing space for air, water and nutrients the roots, as well as provide for future root expansion. Engineered structural soil provides a resource for root growth beyond the traditional tree pit, allowing for much stronger root growth and ongoing tree health. Bitter_orange_-_Citrus_aurantium_08

Denbow has been providing structural soil to many municipalities within the Greater Vancouver and Fraser Valley area. These departments use Denbow’s manufactured soil to allow city planners and engineering departments to add trees for the health and beauty of urban communities.

Contact Denbow’s soil experts today to find out more about how structural soil can work in your city or municipality.

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Nature is Green Infrastructure

Nature is Green Infrastructure

Nature and infrastructure are not independent of each other; on the contrary, nature is infrastructure. From protecting communities from flooding and excessive heat to improving air and water quality, nature is not only a critically important element of infrastructure but also a vital part of human and environmental health. When nature is used as an infrastructural system, it’s referred to as green infrastructure.  images

Green infrastructure can be a highlight of regional and metropolitan planning, helping ensure communities have a safe, livable environment with clean air and water that lasts for generations. Although green infrastructure is often associated with green storm water management systems, it can be used to address a wide range of systems at a variety of scales.

Green systems can be used for wildlife, which are increasingly threatened by human encroachment and climate change. For example, corridors or greenways allow animals to move through human communities; these have the added benefit of being a beautiful space that people want to live near.

Park systems, urban forests, and constructed wetlands also serve as green infrastructure. Constructed wetlands help communities manage water locally and provide habitats for wildlife.

Moreover, green infrastructure practices at the site-scale are used by smart communities for transportation systems (such as green streets) and green roofs, weaving nature into the built environment.

Research shows us that green infrastructure works. Compared to grey infrastructure, green systems are more cost-effective and far more beneficial to people and the environment.  

 

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Soil Structure for Green Roof Media

Soil Structure for Green Roof Media Green roofs or living roofs have become popular over the years. This is because they provide ecological benefits, aesthetic value and creative urban architecture. When designing a green roof, there are several factors to take into consideration. Green roof growing media is an integral part of a functioning green roof system. […]

Where is Structural Soil Used?


Where is Structural Soil Used?

structure-zone-11After some experience with gardening and landscaping, you will find that in some cases, standard soil just won’t do. You may need to provide a better, more solid base for large plants such as trees and bushes to grow successfully. This is where knowing about structural soil will help.

Structural soil contains larger solid particles and provides more structure that normal soil. These added solid particles create a firm structural base while allowing plant and tree roots to weave around the soil pockets. Structural soil is comprised of a mixture of gap-graded gravels, which are typically made from crushed stone, a hydrogen stabilizing agent and clay loam. This type of soil is perfect when planning to plant trees, especially beside pavement sidewalks or roadways.

 

 

Changing Landscaping

Can you picture walking on a beautifully, manicured concrete walkway? Most likely you picture a tree beside this walkway that helps to shape this beautiful image. Structural engineers more often than not will focus on the construction of the concrete walkway or the surrounding road, neglecting the need for a green environment. For this reason, landscape designers are quite important, as they know to choose the right soil for the right result.

By working together with structural engineers, landscape designers are able to successfully grow trees in paved areas. This is normally a challenge due to inadequate soil volume, which is a major requirement for root growth. Soils found under the pavement are usually very compacted, which is the reason why they are unable to support root growth. Only a few trees grow under pavement and when they do, they grow very poorly, dying eventually. It is also worth noting that with the wrong soil the pavement ends up being affected by the root growth. That is why there is need for use of structural soil.structure zone 1

Best Places for Structural Soil

Structural soil has become the best solution for tree-growing in urban settings. This type of soil has been proven to improve tree growth in paved areas, therefore it is the best way to promote street tree planting. Structural soil is used to provide a solid base, which is meant to support masses and at the same time allow for the growth of roots. The result is a perfect crack-free pavement, with a healthy tree growing as expected.

Not all structural soils are the same. They come in different specifications, which are suited for various weather conditions. All the elements that make up structural soil are mixed together. The mix retains a void to allow for water and air movement and gives room for root growth. When used properly, structural soil can allow deep penetration of roots so as to avoid surface heating, which often affects growing trees. Encouraging deep penetration of roots is also good to allow the roots to find sufficient water, necessary for tree growth. This is a great benefit since trees whose roots grow deeply are less likely to lift and crack pavements, leaving you with a great looking pavement and an amazing green environment.

code-walk---streetscapeBoth structural engineers and landscapers benefit from the use of structural oil. Engineers appreciate a firm foundation for the pavement and landscapers realize trees with sufficient root volume, air and water for growing trees. Structural soil is becoming more recognized in urban settings as it provides an excellent solution for the people within these areas. It satisfies the need to enjoy good roads and a perfect environment at the same time. It is a lasting solution for both structural engineers and landscapers.

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