| [College of ACES] | [University of Illinois] | [Illinois CES] |
http://www.gis.net/~dmiller/porpave.html
Obviously, all the answers are not there -- none of us has all the answers, yet.
Subgrade preparation can be modified depending on soil characteristics --
Isn't that the forever tug of war between the project arborist and the soils engineer?
In my experience,
we propose as root-friendly a surface as the project will accept,
then shoot for the least intrusion into the root zone --
suspend the whole kit and caboodle (pre-stressed concrete on piers), or
set the whole shebang on geotextile fabric on existing grade, or
at least minimize base preparation.
I know your query was posted months ago, but if it's not a done deal maybe this can start others talking to get some more ideas out there.
Good luck with your project, George.
Ray Morneau