Page:Survey of Radionuclide Distributions Resulting from the Church Rock, New Mexico, Uranium Mill Tailings Pond Dam Failure OCR.pdf/9

 total inventory of 230Th background in the upper two inches of arroyo sediment is estimated to be 0.30 Ci.

10. Present inability to differentiate between natural background 230Th and contamination-derived 230Th prohibits a clear definition of the 230Th from the tailings pond solution.

11. Sediment samples from the Grand Canyon National Park show no radionuclide levels in excess of normal background.