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probe may be withdrawn for drilling, and then replaced for further data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.