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avoidance; ameliorating reclamation techniques; blending, dilution, and/or burial by <br /> normal overburden and interburden handling; and where necessary, selective handling. <br /> These mitigative measures are also listed in Appendix 6-5, and are discussed in further <br /> detail in Tab 21, Minesoil Reconstruction. <br /> Quality Control and Duplicate Samples <br /> Quality control is an important part of the Nucla East overburden, interburden, and <br /> underburden monitoring program. One aspect of this quality control program is to have an <br /> alternate laboratory facility complete duplicate analyses on five percent of the total <br /> samples. On May 22, 1987 Peabody requested that four Phase I samples be shipped from <br /> InterMountain Laboratory (IML) in Sheridan, Wyoming to Peabody Central Laboratory (PCL) in <br /> Freeburg, Illinois. On November 3, 1987 Peabody requested that four Phase 11 samples be <br /> shipped from IML in Farmington, New Mexico to PCL in Freeburg, Illinois. When combined, <br /> these 8 samples represent 8 percent of the total samples analyzed (100 samples) for this <br /> study. A second part of the quality control program involved having IML complete <br /> duplicate analyses on five percent of the total samples. <br /> IML completed duplicate analyses on six Phase I samples. The duplicate analyses results <br /> are given in Appendix 6-4. Overall , duplicate analyses were quite similar to the original <br /> data. Variation between the original and duplicate analyses data was not significant <br /> enough to change the suitability classification of any sample. <br /> The PCL duplicate data was similar to the original IML anlayses for pH, EC, SP, Ca, Mg, <br /> Na, SAR, AP, NP, ABP, SO4, HCO3, NO3, 504, Mo, Mn, Fe, Cd, As, and Ni. PCL duplicate <br /> analyses for Pb, Cu, Se, and B were 100 to 500 percent higher than corresponding IML <br /> values, but the variation resulted in no change to the suitability classification. PCL <br /> duplicate NH4 values averaged about 50 percent less than the IML data. PCL recorded finer <br /> particle size analyses than IML. In summary, duplicate data variability was not <br /> significant enough to change the suitability classification of any samples. The <br /> variability between labs may be attributed to normal laboratory error and slightly <br /> different analytical methods. <br /> Conclusions <br /> Overburden characteristics within the Nucla East study area reflect the variable <br /> 6-1-39 Revised 04/11/88 <br />