Abstract: An ejector/injector tool for use with cone penetrometers includes a hollow body portion connected at one end with the CPT rod string and connected at the other end with an annular valve body having a central tubular opening. An extendable delivery tube containing a plurality of fluid delivery ports passes through the valve body into the hollow body. A plurality of O-rings in the valve body ensures a liquid tight fit between the valve body and the delivery tube. The interior end of the delivery tube is coupled to a stop ring containing a plurality of fluid paths to permit the entry of fluid into the delivery tube.