The discovery of an old septic tank on your property is not good news. These tanks can be dangerous because they can be so unstable. Even concrete tanks can deteriorate and cave in, and metal tanks can rust through. Search on the Web and you'll find too many stories of kids running through yards who suddenly "disappeared." If you know there's an old tank in your yard, you need to close it up quickly.

The Tank Material Matters

The exact procedure you'd use depends on the material. First, you have to be sure the tank is completely empty—you may need to have a septic contractor pump out the tank.

Concrete tanks are often filled in completely, and metal tanks are often crushed flat and then buried. Newer fiberglass tanks could be crushed in some cases but are often removed. Keep in mind that since even concrete breaks down, you'd still have to be careful in the yard over the years. But you would have taken care of the real problem, which was that huge, space-filled tank.

Note that if you have a large property, you might have more than one tank, or you could have multiple cesspools hidden underground. If you know of one tank in your yard, have contractors inspect the entire property to ensure there are no other hidden dangers.

When Done, the "Ground" Must Be Solid

Whatever method you use to close up the tank, the ground—the soil, the old tank space, and any filler—must be solid. No gaps should be left, and none of the material should have any more room to move. The area should be packed so that, even if the material disintegrates more (such as that concrete), it won't create a hole that people and animals can fall into.

Watch for Continued Settling

Once the tank is covered over, be it with new soil because the tank was crushed or a topped-up layer of topsoil, that soil can continue to settle over time. Keep an eye on the ground there for depressions that could become trip hazards. These depressions, also sometimes called sinkholes even though they are not the cavernous underground holes that the word brings to mind, can still be harmful because when grass covers them, you can't really see them, increasing the risk that you'll trip.

A septic system contractor or a general contractor who handles septic projects can help you from start to finish. Make your yard safe for everyone who walks across it. Contact a septic servicing company like LP Murray for more information.