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To create a stable and level edge for the new paver path, and to prevent future soil erosion onto the pathway, install a small wooden retaining edge. Place two pieces of treated lumber horizontally, stacking them one on top of the other, against the edge of the newly excavated area. Secure these wooden planks by driving rebar stakes through them and deep into the ground using a hammer. Use a spirit level to carefully check that the top surface of the upper wooden plank is perfectly level. If it's not level, adjust by either digging out a small amount of soil or placing small rocks or shims underneath the lower plank until it achieves a level position.