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Peabody anticipates that a certain degree of sampling and laboratory <br />analysis error occurred due to handling Cores 2034E, 2613E, and 2614E in <br />a wet condition during the summer of 1981. Sandoval and Power (1977) <br />stipulate that erroneous nitrate-nitrogen data are generally produced <br />when samples are stored moist under warm conditions. Also, exposure of <br />overburden materials to atmospheric weathering and to microbial action <br />results in significant biological and chemical transformations of <br />organic N to ammonium and ammonium to nitrate (Barth, 1981). However, <br />the chemical and biological transformations in the samples collected <br />from Sites 2034E, 2613E, and 2614E should not have been drastic enough <br />to cause the excessive values which were reported. Although no records <br />are available, the samples may also have been contaminated by drilling <br />fluids or additives (foams). <br />The premine overburden ground water data collected at Sites 2034E and <br />2613E also indicate that premine overburden N03-N values are <br />nonrepresentative. Ground water N03-N values for the three years prior <br />to mining are presented in Table 3. Mean N03-N levels at both locations <br />ar•e well below the U.S.E.P.A, and Colorado Department of Health drinking <br />water standard of 10 mg/l. <br />Mining iras been completed in the vicinity of core hole locations 2034E, <br />2613E, and 2614E (see Exhibits 12-1, Operation Plan and Exhibit 13-2, <br />Reclamation Plan). Much of this area has also been final graded, <br />topsoiled, and seeded during the 1984 through 1986 period. Spoil water <br />discharge data from the southern Wadge mining area is currently <br />available for one spoil spring (BP-0001), one undisturbed by mining <br />spring (DA-0005), and an NPDES sample site (DA-0004). These three <br />hydrologic monitoring sites are shown on Exhibit 7-2, Hydrolog;~ <br />Monitoring Site Location Map. The N03-N data for these three sites is <br />presented in Table 4. Mean N03-N values for all three sites are below <br />the domestic drinking water standard of 10 mg/1 established by the <br />U.S.E.P.A. (1976) and Colorado Department of Health (1977). The <br />undisturbed spring site has the highest mean N03-N value of 8.7 mg/1. <br />• Botlr the premine ground water monitoring data and the postmine spring <br />11 <br />