Just finished excavating for a paver patio. While compacting soil I found a 4x4 area that was very soft and moved while walking on it. I then dug the 4x4 area another 2 feet deep and still it is soft, so I dug another 2 feet, and still the same. Any suggestions on how to handle. I do not want this soft spot to transfer to the top of the patio. Thanks for any suggestions.