All soil in your yard or garden started out as part of the rocky firmament of the primordial planet. Throughout the millennia, it has succumbed to wind and water, breaking down into smaller pieces and mixing with the organic remains of all the plants and animals that have ever lived. The rich soil in the garden supports a variety of plant life, but clean fill dirt must support buildings as well as the weight of the garden.
Clean Fill Supports Topsoil
Topsoil contains nutrients, including nitrogen, phosphorus and potassium, and minerals, including calcium, contributed by long-dead organic occupants. Topsoil contains so much organic matter that it compacts, forming dips and hills as it settles. Clean fill dirt lies below and supports this layer. Percentages of acceptable materials vary from state to state, but the U.S. Environmental Protection Agency allows a variety of materials, including rock and construction materials to be included in fill as long as it contains no toxic or contaminated materials.
What Lies Below
Clean fill dirt, sometimes called clean fill, contains little or no organic matter. It may contain pebbles, gravel and sand -- all the steps from rock to topsoil -- without the organics. Clean fill dirt may settle slightly, but drains easily due to its lack of absorbent organic matter. When ordering this material, ask your supplier to prove that the fill is clean by providing certification by a laboratory and insist on an invoice or load ticket that guarantees the lack of contaminants in the entire load.