Abstract: A method for performing nuclear depth density tests in coal stockpiles and a special thin wall housing for the probe used in the tests. A drilling rig employs continuous flight augers to drill an access hole through the entire depth of the coal stockpiles. The nuclear density probe is inserted into the special housing. The housing is then screwed onto an initial section of drill pipe and an electrical cable extending from the probe is threaded through the drill pipe section. The winch line of the drilling rig is used to progressively lower the housing into the access hole. As the housing and probe are lowered, additional sections of drill pipe are added to the drill string and the electrical cable is fed through each added pipe section. When the housing reaches the bottom of the access hole, the cable is plugged into a scaler instrument located at the surface. Tests are performed at two foot intervals as the probe is progressively raised in the access hole by the winch line.