One overcast and dreary day about two weeks ago, Silva Cells were installed in a tree installation at a car park in Derby, UK. (I was just informed, by the way, that “Derby” is pronounced “Dahr-bee,” much to my embarrassment, thankfully I didn’t say it out loud too often). The Connecting Derby site is a project of the Derby City Council and was installed by Bam Nuttall and UPM Tilhill.
The installation occurred at the intersection of Abbey Street and Monk Street.
The Silva Cells will provide soil for large, mature tree growth for 20 trees along the perimeter of the car park.
Many of the planting areas are linked, which is ideal because it allows the trees to share soil volume (shared soil volumes provide anywhere from an additional 20 – 50% of usable soil for each tree).
After the frames were laid out, secured with spikes, and wrapped with geogrid, they filled the system with soil in lifts. Walking around the soil in the system (don’t step on the beams of the frames!) will provide an adequate amount of compaction.
A total of 838 frames were installed in a two-deep system that will provide between 10.6 and 13.3 cubic meters (373 – 469 cubic feet) per tree, plus additional benefits from soil sharing where possible.
Compacting the perimeter backfill after each lift is critical!
Excess geogrid gets wrapped over the top of the system and zip-tied to the decks.
Tree openings are kept free of soil during the installation using plywood sheets.
The tree wells will be hand dug out in order to plant the trees along the perimeter of the car park.