Recently, the Cornell Urban Horticulture Institute, headed by Nina Bassuk, published a 57-page Comprehensive Guide to CU-Structural Soil.
This is THE publication to share with your municipality’s engineers and leadership, to show the why and how of CU-Structural Soil.
CU-Structural Soil®, also known as CU-Soil®, is a two-part system comprised of a rigid stone “lattice” that meets engineering requirements for a load-bearing paving base, and a quantity of uncompacted soil that supports tree root growth.
The first section of the Guide discusses the role of soil volume and how to calculate how much soil volume a tree needs. No matter how well matched your tree species is to its site, limited soil volume is something few trees can abide, much less thrive in.
The Guide goes on to give the case for CU-Structural Soil in particular, and answers FAQs like “How much CU-Soil will I need?”, “How do you plant trees in CU-Soil?”, “Can it be retrofitted for use under existing trees?”, and “How is irrigation and drainage handled?” It also explains how to obtain CU-Soil that meets quality control specifications. (This, by the way, is why CU-Soil is licensed—to ensure quality control. Otherwise, anyone could mix up rocks and soil and claim to be selling “CU-Soil.”)
Next, the publication addresses specific scenarios where CU-Soil will be useful, such as trees in plazas and parking lots, growing larger trees in parking lot islands, freeing existing trees from tree pits, saving existing trees threatened by construction, using CU-Soil under permeable pavers and porous asphalt, and using it with turf.
The Guide goes on to give case studies in Ithaca, Brooklyn, and Birmingham Alabama. The last section provides extensive installation specs and design details. Check out the Comprehensive Guide to CU-Structural Soil.