Abstract: An apparatus for removing a liquid and a material that is not a liquid in contact with the liquid from a borehole penetrating the earth includes a mechanical pump configured to pump the liquid and material from the borehole and a motor configured to be coupled to the mechanical pump. The apparatus further includes a variable speed motor drive configured to be coupled to the motor. The variable speed motor drive is configured to energize the motor in continuous cycles to operate the pump, each cycle comprising operating the pump at a first speed for a first time interval to remove the liquid and not the material and operating the pump at a second speed greater than the first speed for a second time interval to remove the liquid and the material.