Material sources are locations, typically outside the highway corridor easement, from which rock and soil materials may be mined and processed for new construction or maintenance needs. Material sources are used for many of ADOT's highway construction projects. They may also serve ADOT as repositories for excess materials generated by construction or maintenance activities. For any given project, the contractor supplies the needed materials, by using either an ADOT-licensed source or a contractor-furnished source. Whether the material source is an ADOT-licensed source or contractor-furnished source, it requires environmental approval prior to every use.