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s <br />NOTE: Ideally, pressurized ionization chambers (PIC) should be <br />used while making gamma-ray exposure measurements because <br />accurate gamma measurements cannot be obtained with a poorly <br />calibrated scintillator survey meter. To assure reproduci- <br />bility of the scintillometer readings, the instrument should <br />be carefully calibrated and periodically cross-checked with <br />a PIC. Gamma measurements should be made during normal dry <br />weather and not following rainfall or when the soil is wet <br />or frozen. While taking readings, the instrument should be <br />held out away from the body. A double reading technique, <br />i. e., shielded versus unshielded, may be necessary in areas <br />where shine from mine wastes or tailings piles may present a <br />localized gamma source. The radioactive material or radia- <br />tion intensity used to calibrate the survey instrument <br />should be noted in the application. <br />III. SOIL SAMPLING TECHNIQUES <br />Soil sampling and analysis should be conducted to determine the pre- <br />mining radionuclide concentrations in order to develop a reclamation plan to <br />be consistent with reclamation standards. Recommended techniques are as <br />follows. <br />1. Using the gamma survey, affected lands should be broken up into <br />areas of relatively similar activity. <br />2. Soil and bedrock material of each similar area should be sampled by <br />not less than ten auger holes to a depth of six feet. All material <br />from the 10 auger holes should be thoroughly mixed and an aliquot <br />of the composited samples taken for laboratory analysis. The 10 <br />soil sample'locations should be randomly selected. Soil sample <br />locations forming each composited sample should be noted on the <br />gamma survey..map.. <br />NOTE:` Down-the-hole gamma logging may function as an alternative <br />means of establishing bacl~:ground in the surface six feet of <br />the soil and bedrock material. However, before this method <br />can .be acceptably used in place of soil sample collection <br />for ,quantitative analysisv the operator must develop an <br />acceptable calibration curve which is based on actual con- <br />tTations in the soil. <br />- 2 - <br /> <br />