[CANUFNET] Porous parking x-section for residential sub-divisions

[Jeremy Gye]

All you Sudoku puzzle fans, its time for a break...here is a better puzzle:

Has anyone got any input regarding a x-section detail or specification for
the following application:

Context: new sub-division development with mature trees protected by
covenant.  

Needed: a construction detail for driveway and parking elements that must
encroach into the calculated critical root area.   

Considerations: 
	- large shallow-rooted trees on relatively flat ground with a root
restricting layer at 24 - 30"
	- impacts to tree root impacts must be miminal
	- hydraulic conductivity and healthy gaseous exchange must be
maintained to the root horizon beneath the drive and parking area 
	- assume organic (LFH) layer will be removed within the footprint of
the drive and parking area.
	- assume two possible sub-soil scenarios:
		1) a relatively trafficable mineral soil (e.g. a gravelly
loam)
		2) a more fragile mineral soil horizon (say a silty loam
with a well defined Ah layer)
	- the finished surface must be attractive and stable

I've considered a porous paver product (e.g. SF Rima or Aqua-Pave), but the
manufacturer's specified sub-grade requirements are lethal to the tree roots
(i.e. require excavated sub-grade of about 28").

Any thoughts?

Jeremy Gye
Gye & Associates - Urban Forestry Consultants Ltd
(250) 544-1700