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iii iiiiiiiiiiiu iii <br />999 <br />Bulldog Mine <br />Tai[inns Evaluation <br />April 17, 1997 <br />Meeting Notes: <br />Seepage first noted at Lower Pond in 1978. <br />Series ofCorrective Actions were implemented from 1982 -]983 and effectively <br />retarded seepage and stabilized embankment. <br />~ Mill production was curtailed in 1985. <br />Water levels in piezometers and monitoring wells declined rapidly. <br />During post-operational monitoring period from 1985-1989 metal levels were <br />erratic and samples difficult to secure. <br />Samples taken from the few weQs that contained water between 1989-1993 <br />reflected more stable water quality. <br />Summary of azchived information presented to DMG in April 1996 did not support <br />a conclusion that the tailing do not pose a potential threat to ground water. <br />HMC and DMGconcluded during May 1996 meeting that the placement of <br />monitoring wells would be difficult in a fracture flow system surrounding the <br />impoundments and would provide unreliable and erractic information. <br />Alternative would be to characterize the tailings source. <br />Tailings characterization program was initiated in mid 1996. <br />Characterization program included both geotechnical and geochemical evaluations <br />of both impoundments. <br />Geotechnical Testing; Geochemical Testine: <br />l) Consolidation /) ABA <br />2) Permeability 2) Mineralogic Analyses <br />3) Index Properties 3) Chemical analysis ojpore wafer <br />• moisture 4).4ttenuation <br />• detuity 5) O.rygen consumption/profile <br />• spec. gravity <br />• atterberg limits <br />• sieve analysis <br />Characterization Results: <br />1) Tailing in both impoundments are saturated and consolidating at slow rate. <br />2) Low vertical hydraulic conductivity compazed to estimated infiltration <br />indicates rate of pore water migration very slow and saturated conditions <br />will be maintained. <br />3) Pore water and batch leach test extracts meets ground water quality <br />standards except for manganese, lead and antimony. <br />4) Mineralogic evidence, oxygen consumption measurements and pore water <br />chemistry indicate sulfides stable. <br />5) Future oxidation not likely given saturated conditions. <br />6) Attenuation tests using pore wale and site soils indicate Creede Formation <br />have high retardation capacity and manganese, lead and antimony would be <br />immobilized by sorption, if seepage occurred. <br />7) Further dilution would occur if seepage were to mixed with area ground <br />water using conservative estimates. <br />