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Bullda¢ Mine TailinRS Paruls Eva(rmtian <br />5.0 GEOCHEMICAL ANALYSES <br />A geochemical testing program was performed to assess the geochemical characteristics of solids <br />and pore waters within the Bulldog tailings as it relates to potential for impact to ground water in <br />the azea. Specific investigations included: (1) acid-generation potential of tailings including <br />acid-base accounting (ABA) analysis of the tailings solids and mineralogic analyses of the <br />tailings solids, (2) in situ oxygen profile/flux measurements at the surface of the tailings, (3) <br />synthetic precipitation leach test (SPLP) on the tailings solids, (4) chemical analysis of tailings <br />pore water, and (5) batch leach attenuation tests using tailings pore water and local sediments. <br />The purpose, methods, and results of each of these investigations are presented below. <br />5.1 Acid Generation Potential of the Tailings Solids <br />The current and future acid generation potential of tailings were evaluated using ABA and <br />mineralogic analyses of the solids. Because acid generation in sulfide materials consumes <br />oxygen, the results of the ABA and mineralogic analyses are compazed to field measured rates of <br />• oxygen consumption and oxygen concentration profiles to determine if acidification reactions are <br />currently occurring within the tailings. <br />5.1.1 Acid Base Accounting (ABA) Analyses <br />ABA testing defines the balance between potentially acid generating minerals and acid- <br />neutralizing minerals in a rock or soil sample. In ABA analyses, the acid generation potential <br />(AGP) is a measure of the amount of pyritic sulfur within the material, and the acid neutralizing <br />potential (ANP) is a measure of the amount of cazbonate minerals (particulazly calcite). The <br />results of all tests aze reported in equivalent units of tons of CaCO3 per kiloton of material <br />(T/kT). <br />ABA test results aze interpreted by either computing the net neutralization potential (NNP) of the <br />material (NNP =ANP -AGP) or by computing the ratio of ANP/AGP of the sample. Samples <br />with positive NNP values or with ANP/AGP ratios which aze greater than one have a lazger <br />amount of neutralizing material available than acid generating material. The State of Nevada <br />. (September 14, 1990) considers materials which have ANP/AGP ratios above l.2 to likely be <br />non-acid generating. The Bureau of Land Management (BLM, 1996) uses a more conservative <br />Hamesmke alining Campam~ Shepherd llil/er. Inc. <br />pv'dlnn„lm.x rr 24 dpn( /{. /997 <br />