I dunno, I've been paving my driveway with shale for 13 years,...
I like it because it crushes easy, makes a firm surface and does not put any petrochemical run off into my yard which could leach through my property and potentially into my well (I live in the Saratoga Sand Plains),...
I dislike it because I have to pop a bunch of cash for several new yards every few years and regrade it as it disintegrates to a soil like consistency in a short time, although I do thoroughly enjoy renting and playing with the skid steer for that day,...
then again in spots here and there, it does it does get packed fine and tight and the rain will runoff as opposed to draining through,...
I reckon these smart guys know a lot more about engineered shale disposal than I do,...