A sinkhole is best repaired by excavating to rock
and then building an aggregate filter in the hole.
Step 1: Excavate the sinkhole down to rock if possible.
Step 2: Put a layer of large stones in the hole (cabbage size).
Step 3: Put a layer of smaller stones on top (fist size).
Step 4: Put a layer of gravel on top of the small stones.
Step 5: Cover the gravel with a geotextile fabric. This prevents
the next layer (sand) from being lost through the gravel.
Step 6: Cover the geotextile fabric with a layer of coarse sand.
Step 7: Fill the remainder of the hole with soil. This can be
layered to match the existing soil profile.
Ideally each layer is six inches to two feet thick. When solid rock
is encountered near the surface, drop off the bottom layers (that is
start with smaller stone size) or use thinner layers. It is important
that the bottom layer be larger than the solution channel opening in
the bedrock. The objective is to provide an open path for percolating
water so that it can't carry away soil and cause another sinkhole. The
repair, as described, also provides good filtration of infiltrating