While the Silva Cell system can be optimized for tree growth or stormwater management alone, ideally we try to promote both simultaneously. Our standard details lay out the basics, but there are still some questions about just how the Silva Cell functions on sites where it is serving as an integrated tree and stormwater management system. Below are some of the most frequently asked questions and answers.
One benefit the Silva Cells provides is to reduce the irrigation usage – is that because the soil within the Silva Cells stores some of the stormwater?
Irrigation use is reduced in Silva Cell stormwater applications because site stormwater is distributed through the Silva Cell system. In designs with pervious pavement, the stormwater is directed to the infiltration basins and will provide water to the trees rooting within the Silva Cells. Bioretention soil mixes are used in Silva Cell stormwater applications, which can store water within the soil macropore space (20% total soil volume). In designs that don’t utilize pervious pavement, stormwater can be routed in to the system using alternate methods.
How do we ensure the moisture is kept within the Silva Cells?
The Silva Cell system is not designed to “contain” water unless native soils have virtually no permeability. The standard Silva Cell details have no water barriers, and are designed to allow for natural infiltration.
Is there any device, such as a moisture sensor, that can be put in the Silva Cell to indicate that there is enough moisture in the soil and the irrigation system can be reduced?
A moisture sensor can certainly be included, and could easily be part of the irrigation system. The need for this would be affected by the porosity of the native soils adjacent to and below the Silva Cells, as well as typical rainfall for the area.
Will an irrigation system need to bet in to the Silva Cell system, or can it remain within the planters only?
An irrigation system is still recommended for overall tree health.
These are just a few of the most commonly asked questions about using the Silva Cell in a stormwater application. We know there are plenty others… if you have something you’d like answered, please leave a note in the Comments section and we’ll let you know!