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• interval in Peabody Appendix 6-5. Effective mitigative measures will include avoidance; <br />ameliorating reclamation techniques; blending, dilution, and/or burial by normal overburden and <br />interburden handling; and where necessary, selective handling. These mitigative measures are <br />also listed in Peabody Appendix 6-5, and are discussed in further detail in Section 2.05.4(2)(d), <br />Topsoil (Redistribution). <br />Quality Control and Duplicate Samples <br />Quality control is an important part of the New Horizon 2 overburden, interburden, and underburden <br />monitoring program, One aspect of this quality control program is to have an alternate laboratory <br />facility complete duplicate analyses on five percentofthe total samples. On May 22,1987 Peabody <br />requested that four Phase I samples be shipped from InterMountain Laboratory (IML) in Sheridan, <br />Wyoming to Peabody Central Laboratory (PCL) in Freeburg, Illinois. On November 3, 1987 <br />Peabody requested that four Phase II samples be shipped from IML in Farmington, New Mexico <br />to PCL in Freeburg, Illinois. When combined, these 8 samples represent 8 percent of the total <br />samples analyzed (100 samples) for this study. A second part of the quality control program <br />• involved having IML complete duplicate analyses on five percent of the total samples. <br />IML completed duplicate analyses on six Phase I samples. The duplicate analyses are given in <br />Peabody Appendix 6-4. Overall, duplicate analyses were quite similar to the original data. <br />Variation between the original and duplicate analyses data was not significant enough to change <br />the suitability classification of any sample. <br />The PCL duplicate data was similarto the original IML analyses for pH, EC, SP, Ca, Mg, Na, SAR, <br />AP, NP, ABP, SO4, HC03, N03, SO4, Mo, Mn, Fe, Cd, As, and Ni. PCL duplicate analyses for Pb, <br />Cu, Se, and B were 100 to 500 percent higher than corresponding fML values, but the variation <br />resulted in no change to the suitability classification. PCL duplicate NH4 values averaged about <br />50 percent less than the IML data. PCL recorded finer particle size analyses than IML. In <br />summary, duplicate data variability was not significant enough to change the suitability classification <br />of any samples. The variability between labs may be attributed to normal laboratory error and <br />slightly different analytical methods. <br />• Revised 27 Aug 2002 37 <br />