Fill dirt is used to fill holes or build up ground in construction projects. This type of dirt is usually subsoil, also known as substrata, which is a material found under topsoil. It is basically partially broken down soil that contains clay, sand, and other materials. Fill dirt is typically obtained when a construction project requires the workers to dig a deep hole and begin the construction there. The subsoil is removed from the site and kept for later use or sold or given away to another individual or company who can use it.
A popular use of fill dirt is to build up ground before constructing a building to reduce the chances of flooding. This is normally done when the construction site is low-lying, and the area receives enough rainwater to potentially flood the to-be-constructed building. Fill dirt has been used in this manner before the construction of everything from airports to homes. This type of dirt has even been used to help create man-made islands. Other smaller-scale construction projects that use fill dirt are usually performed by a landscaper to build waterfalls, pools, or just provide a more interesting texture to the landscape.
Another common use of subsoil is highway maintenance. The area surrounding a road can gradually erode due to rainwater, people parking on the roadside because of car trouble, and other factors. When this happens, the roadway maintenance authority might pay for the sides of the road to be built up in order to make it safer for drivers to pull over.
There is generally an abundance of fill dirt no matter the region, so the material is inexpensive. If the buyer cannot pick up the dirt, however, the costs of delivery can significantly increase the price. For example, it is not unusual for delivery alone to be three to five times the cost of the dirt. This does not factor in the cost of spreading the dirt, however; most companies that sell fill dirt do not spread it, only sell and possibly deliver.
Fill dirt is not only used for large construction projects; individuals building up their backyard for various reasons sometimes use the dirt. In some cases, the individual can simply call a few construction companies to ask for free dirt. This can sometimes save a lot of money, but it is necessary to have a vehicle capable of moving the dirt. The construction company is doing the individual a favor by giving him or her the dirt; they likely will not deliver it too.