Sean
I hope I do not sound sarcastic with this answer. What I would do is build the wall up slightly ΒΌ~1/3, lay the fabric in place folding the extra overtop of the rocks, then back fill with the dirt and compact. Fold the fabric back over the dirt and build another layer of the wall and repeat all the above. Work like that until almost reaching the top of the wall. Just before laying the finial top course of stone, fold the fabric over the rock and place the top rocks on the fabric, then backfill as before. Should you need to "go behind the wall" for any future construction you will not have to cut away the fabric and attempt to insert more.
Tom Trigg
Sorry Sean, thought you were talking about building a wall. Tunnel portal is just slightly different. In my case
I cut the fabric into almost triangular shapes, with a "square" extension on one corner. The "extension" ran along side the tunnel exterior wall (about 10 inches). The triangular portion splayed out along the backside of the retaining wall. I used duct tape to hold in position during construction. I'm sure the tape has long since rotted away, leaving the fabric to be held in place by the dirt and rocks.
Sean: Looking good my friend. Looks to me as if you have conquered the problem.
smcgillYes nothing a couple of asperin couldn't fix!
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