A borrow pit, also referred to as a sandbox, is a large hole that has been dug for a particular purpose. The hole left behind after the material has been harvested from a construction site is called a "borrow pit." Frequently, construction crews will dig borrow pits in order to gather gravel, soil, and sand for use in another location.
There are many things that can be done with a borrow pit once a construction crew has finished digging inside of the initial hole. Some pits are used as landfills, while other pits may form recreational areas. In fact, it is not uncommon for a municipality to fill a pit with water, resulting in a small manmade pond or a large lake. Other pits may be turned into wildlife habitats by adding certain elements, such as water, to the pit area. Rarely do municipalities decide to fill a pit in with extra sand or other material, though this is possible.
The digging of a borrow pit falls under the engineering discipline known as earthworks. Earthworks projects consist of engineering feats that include transporting large amounts of soil or rock from one area to another. Borrow pit construction may seem relatively easy to accomplish, though this type of digging actually requires an extensive amount of analysis prior to the first dig.
Engineers must be sure that the amount of soil dug from a pit area will not disrupt the earth. This specific type of engineering, called geotechnical engineering, is a complex process. Prior to the invention of the computer, geotechnical engineers were forced to calculate the degree to which the earth would shift during digging by hand. Today, computer programs make these types of calculations simpler.
Since massive quantities of earth must be moved in order to build roads, railways, canals, buildings, and other structures, the invention of various industrial tools has made this task easier. Bulldozers, loaders, production trucks, graders, and many other large pieces of equipment are often used to move soil from one place to another. Without these machines, digging a borrow pit would take years instead of months or weeks to accomplish.
A borrow pit's volume really depends upon the construction project at hand. While major roads and freeways may take multiple tons of gravel to build, small projects may not require much soil. No matter what the end project may be, borrow pits can always be turned into something useful that benefits a community.
