I have a sinkhole in my front yard, above the septic tank. We bought the house 2 years ago. The sellers had a new septic tank put it. At the first rain, we got a sinkhole. Called out Alpha Omega, who put in the new tank, and they said it was a broken sprinkler head that caused the hole. Just had a lot of rain, and the sinkhole is even bigger. Part of the walkway has fallen in. Called out Alpha Omega again, and they said "It's gonna take a lot of dirt to fill that in." They said it was caused by the rain.

Typically they are pumped, perforated, and then filled in according to the procedure desired by the local regulatory authority, usually the county health department. Check with your municipality; permit may be required.

Agreed, if not removed, ( few are) they are broken up, or holes placed in them, and filled. Most areas have a special county or city department that is over septic tanks, the required drain fields and more