How You Use Fill Dirt Depends on the Type of Fill Dirt You Have
When you are planning to build a structure on your property, perhaps a garage, a swimming pool, or a new road, or to install some hardscaping or landscaping, you will likely need to bring in some dirt. The project you are planning will determine the type of dirt you need. If you have little experience with sizeable construction projects, you may not know that different projects need different types of dirt. Using the right kind of dirt for your project is key to the project’s successful completion.
Here is an overview of common types of dirt and how it is used.
Fill dirt is the material used to fill holes and low areas or build up ground elevation on construction sites. Fill dirt is commonly made of subsoil, which is a found about 12 inches below the topsoil. It consists of partially broken down soil that contains clay, sand, silt, and stones, and any other materials found in the source ground. Unlike topsoil, fill dirt is stony, heavy, and inorganic. Desirable fill dirt is mostly inorganic. Good quality, inorganic, clean fill dirt consists of at least 50% clay. Its inorganic qualities make it ideal as fill because it does not decompose and settle like organic soils are prone to do. It will not support plants and vegetation.
Fill dirt is used in construction projects. It is perfect for site preparation and base for a home or building, an addition, road, or sidewalk. These structures need a solid, stable base of support. For this purpose, you may need to use “clean” fill dirt.
For fill dirt comprised of natural subsoil, the term “clean” fill dirt means the dirt has been screened and determined to be suitable for base fill dirt. It has been screened to remove contaminants such as roots or other objectionable materials. If the fill is not subsoil, but instead is made of concrete pieces, bricks, gravel, or asphalt paving materials, “clean” fill means it is inert and is not a fire hazard and poses no danger to groundwater. When ordering clean fill, you should have your supplier certify that it is clean.
Fill dirt is ideal for:
- changing the elevations on your property,
- supporting a retaining wall,
- correcting poor drainage near your foundation or elsewhere on your property,
- supporting a new swimming pool, or
- filling in low areas or holes. For example, if you wish to demolish or remove your inground swimming pool, your contractor will fill the hole with fill dirt.
Fill dirt used in construction projects must meet specifications for gradation outlined by the project’s geotechnical engineer. The supplier of clean fill should be willing to certify in writing that the fill is virgin material from a commercial or non-commercial source and that all of the materials in the fill dirt are natural and do not contain any additives or dangerous materials such as refuse, rubble, muck, metal, glass, wood, or other foreign materials.
Fill sand, like fill dirt, is used to fill low areas, but fill sand and fill dirt are very different. Fill sand is made of fine particles of rock that have been broken down and eroded into sand over thousands of years. It is good for improving drainage around wet areas and to fill areas around septic tanks and ponds where drainage is important. Sand tends to be prone to shifting and displacement, while fill dirt is very stable. As such, fill sand is not good to use as a base for building structures. Fill sand with more than 50% sand is good fill for areas that will be used for plants, and then topped with several inches of topsoil. In summary, fill sand is best used in projects that will involve regular exposure to water and moisture.
Rock fill contains big rocks, often larger than a football, to fill in deep openings. You can also use the large rocks to landscape your yard. It usually comes from blast sites or deep excavation sites. To grow grass or plants, you will need to top it with heavy layers of organic clean topsoil perhaps followed by compost, mulch, or manure.
Topsoil is organic. It contains nutrients that will support grass and plants. Topsoil is used for gardens and landscaping plant materials. If you just need to fill shallow low spots in your landscape garden or yard, topsoil works well. It contains few, if any, rocks or other debris. Clean topsoil is easy to spread and level with a hand rake because of its purity. Topsoil will not support the hardscape features of your garden. You need fill dirt for those.
How do you know if your contractor delivered the kind of dirt you were supposed to get? If you have doubts about the dirt composition, you can have it tested by the county agricultural extension office or a reputable lab. Also, before you order your fill dirt, be sure that you have checked all applicable Federal, state, and local laws and regulations to determine whether permits are needed and the type of fill you can use.
Contact a Reputable Dirt Supplier
Before you order dirt for your project, contact a reputable supplier to discuss your project needs. Depending on the complexity of your project, you may need different types of dirt for different project phases. Before you buy dirt, contact a professional. A reputable supplier can answer your questions and make sure you get the right dirt for your project for a reasonable price. Some professional fill dirt companies even offer a free dirt delivery.