Q: I built my home in 1986. The builder buried trash in my back yard and this created a continuous sink hole. I have had this fixed 3 times only to see it come back. In June of 2009 we seemed to have fixed it right by putting up a small retaining wall. A big storm in September brought back the sink hole. The landscape company thinks the damage is occurring underground and that we may have a spring. Do you have any idea what may be happening?
A: It sounds like you have a trash hole that was never quite fixed correctly. Underground springs are almost never a cause of sinkholes. It’s simply caused by buried building materials gradually decomposing and sinking.
Repairing a sinkhole is relatively straightforward but it may require machinery to get the job done right.
Follow these steps:
1. Check the location of buried utility lines before you dig. Call 811 for free utility location service.
2. Enlarge the surface opening to access the entire cavity. Look for decaying debris and confirm the cause of the problem.
3. Remove any large pieces of undecayed debris.
4. Fill the entire cavity by adding loose fill dirt in 12-inch layers. Pack the soil firmly after each 12-inch layer to prevent future settling. Failure to pack the entire cavity may cause another sinkhole in the future.
5. Once the cavity is filled, establish grass or other plants on the bare soil. It’s probably not a good idea to plant a tree in this area for at least a couple of years. After that time, you can be pretty sure your problem is solved.