So we moved the tiles back 12 inches, revealing a 12 inch wide margin of dirt that still needs to be dug out. We started on the back wall. The digging was fairly easy, but as we got to the actual decomposed granite walkway, it was apparent that this whole approach was badly thought out.
There is nothing between the rock and decomposed granite of the walkway and the dirt of the raised garden except a (now badly deteriorated) stretch of garden fabric. As I removed the dirt from the raised garden, the rock and decomposed granite then collapsed into the pit of the raised garden.
In addition, digging on around revealed a couple of very large rocks still in the raised garden, in the upper right corner of the picture below.
We used the jack hammer to break these up so that we can remove them.
We also had to jack hammer out some rock in the opposite corner.
All of this work has been substantially delayed because of frequent rains which both fill the pit and make all the dirt and rock too wet to work in, so it's been months since we have been able to make much progress.
Our objective at this point is to pour a retaining wall around the perimeter of the raised garden pit, to hold out the rock and decomposed granite, and to be the base on which to build a new raised garden using 6x8 inch limestone blocks instead of the railroad ties. We have 40 bags of concrete in the garage waiting to be used for this wall, as soon as we can finish the digging and it's dry enough to work.
