Abstract: Subsurface material property measurements, such as soil or chemical properties, are obtained in situ by a direct push method that includes rotating a ring bit at the end of a casing to drill through subsurface materials, lowering a measurement probe through the advanced casing, extending the lowered measurement probe through the ring bit, and advancing the extended probe through the soil at a controlled rate while gathering material property data from sensors attached to the probe. The probe may be withdrawn for drilling, and then replaced for further data gathering.

Abstract: A tool latching and retrieval system allows the deployment and retrieval of a variety of direct push subsurface characterization tools through an embedded rod string during a single penetration without requiring withdrawal of the string from the ground. This enables the in situ interchange of different tools, as well as the rapid retrieval of soil core samples from multiple depths during a single direct push penetration. The system includes specialized rods that make up the rod string, a tool housing which is integral to the rod string, a lock assembly, and several tools which mate to the lock assembly.