2012 Cherry Street Silva Cell: Urban Tree Canopy Sustainability and Stormwater Reduction Project
Maintaining and increasing the urban tree canopy is an important part of reducing stormwater runoff in the City of Burlington as trees intercept rainfall within their canopy and allow the water to evaporate back into the atmosphere rather than reaching our drainage systems. Additionally, tree planting beds that are designed to provide the tree with sufficient un-compacted soil volume (and thereby encourage large, healthy canopies) can also be used to soak up stormwater. The water is available for irrigation of the tree which, in return, will pull the water into its roots and evapotranspirate it back to the atmosphere. Excess amounts of water are filtered through the soil media and returned slowly back to the drainage system. It is the perfect partnership!
The challenge hinges on providing the tree with the necessary uncompacted soil volume in a highly urbanized environment where the soil is compacted due to the need for pavement systems that can support traffic,. However, some technologies have emerged which can provide the structural support necessary for the urban environment while maintaining uncompacted soils for the tree and for stormwater storage and filtration.
The Burlington Stormwater Program and the Department of Parks are working together to install a tree based stormwater system on Upper Cherry Street using Silva Cell technology. This modular frame/deck system supports the pavement systems and allows utilities to pass through the soil and frame structure.
The total cost is approximately $40K, and is funded through the Burlington Stormwater Management Program (supported by Stormwater User Fees) and a 319 Grant through the VT Dept. of Environmental Conservation ($26K).
Current Status: Unfortunately, the inlet to the Cherry Street Silva Cell is currently blocked as an adjacent landowner reported experiencing basement moisture problems shortly after the Silva Cell was installed. While measures were taken during the design and construction of the silva cell (including a liner on the basement side of the silva cell and an underdrain) we have not been able to resolve whether or not the silva cell, or other local conditions (such as groundwater, or the intense rain storms of 2013) were the cause of the basement water intrusion. We are working to evaluate other possibilities for re-opening the silva cell if possible. For now, the tree, at least, has much more soil volume than the average urban street tree.
