A borrow pit, also known as a sand box, is a term used in construction and civil engineering. It describes an area where material (usually soil, gravel or sand) has been dug for use at another location. Borrow pits can be found close to many major construction projects. For example, soil might be excavated to fill an embankment for a highway, clay might be excavated for use in brick-making, gravel to be used for making concrete, etc.
In some cases, the borrow pits may become filled with ground water, forming recreational areas or sustainable wildlife habitats (one such example is the Merton Borrow Pit, near Oxford in central England, excavated to provide materials for the nearby M40 motorway). In other cases, borrow pits may be used for landfill and waste disposal.