Is there anyway to use the text label or naming label command to show the thickness of the material of the site improvement?
Check out the TBC Macros Forum. We have written a TML that creates a Site Improvement Legend, that gives a color coded legend that describes the Site Improvements assigned to a Project and the layers that make up that SIte Improvement and the thicknesses of each layer. This is exactly what I think you are looking for. I posted a Video of the workflow the week before Christmas (or thereabouts). The TML is called Site Improvement Legend
Here is the Link
TML - Site Improvement Legend