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Sinkhole remediation: Reverse grading technique

To fill in small sinkholes, fill the hole beginning with larger boulders or rocks at the bottom. Follow with cobble, then gravel, then sand, and finally a clay layer or a plastic liner. Top with 8–12 inches of soil.

Placing larger material at the bottom provides support and helps prevent another collapse while the smaller material stops water from moving the soil downward into the void in the bedrock.

This method may not work unless the larger material is placed directly on bedrock.

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