A method for field installation of access tubes for nuclear depth moisture and density equipment is described. After review of previous installation methods, it was concluded that a special drilling unit was required to auger the heavy clays encountered in Oklahoma. The equipment is described in detail, as is the exact procedure used in field installation of access tubes beneath highway pavements. Using the equipment and methods described in this report, 30 test sites of three access tubes each were installed during the summer of 1966. More test sites are planned for future installation.