Wells drilled to date on the Hanford project represent and initial investment of over one million dollars. These nearly six hundred wells have been used and will continue to be used for observation and monitoring purposes of direct interest to ground disposal of radioactive wastes. Through measurement of depth to the water table the changing gradients as a result of large volume waste disposal are determined and direction of ground water flow established. The extent of contamination in ground water is measured in samples dawn from these wells. Aquifer permeability is measured and ground water velocity predicted from pumping tests carried out out in these structure