Suspended pavement trenches with adequate amounts of soil are a great solution for growing healthy, mature street trees — downtown Charlotte and the Christian Science Center in Boston are just two examples of how fantastic the results can be. These two systems are 25 and 43 years old, respectively, and the trees look incredible. Still, these were expensive projects with custom designs that are out of the realm of a typical budget.
For sites where street trees are being planted nearby adjacent open soil volumes such as lawns and parks, the Silva Cell can be used to create an underground access tunnel for tree roots (see our standard detail at the top of this post or download the full set from our website). It can take as little as a single row of Cells for this design to work. This application, which we call a break-out zone, is an easy, inexpensive, and practical solution for sites and projects where there is less money for high-priced custom systems.
Take these two photos of towns in the Boston area, above and below, that I pulled from Flickr. Both show street trees that are mere feet from open planter areas with significant volumes of soil that they could utilize — but they are prevented from accessing it by sidewalk paving.
Just a single row or two of cells could be used to span that distance, providing the trees with a route to access the undisturbed soil on the other side. This is just one application for the Silva Cell, and it won’t necessarily be the right solution for every site — but for many it will, and it is one of the most cost-effective way to provide the tree with the soil it needs.
For more information about estimating the price of a Silva Cell system, visit our Cost page.