2023-04-19_PERMIT FILE - C1981010 (97)

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This comparison shows that average column leachate concentration for most of the • key parameters and disposal options are above average groundwater concentrations. This fact reflects the high local groundwater quality. However, most leachate concentrations are below water quality criteria. Barium exceeds existing ground- water quality for all disposal options, but does not exceed water quality cri- teria. Aluminum is below water quality criteria. Boron leachate concentrations are well above existing groundwater concentrations for all disposal options,. and boron also exceeds water quality criteria. Chromium exceeds existing groundwater for all options, but does not exceed criteria. Molybdenum pit bottom and spoil bench leachates exceed existing groundwater quality, while spoil trough leachate is about equal to existing groundwater levels. Molybdenum leachate exceeds water quality criteria. Sulfate spoil trough leachate exceeds existing quality and water quality criteria. Vanadium leachate concentrations are well above existing groundwater quality but in spoil trough leachate, it is about equal to water qua- lity criteria. Manganese spoil bench and spoil trough leachates exceed existing groundwater quality and water quality criteria. c• In summary, the column leaching studies indicated that if a Leachate occurs, only boron and molybdenum concentrations would exceed existing groundwater quality and water quality criteria for all disposal options. Sulfate and manganese with spoil trough disposal and manganese with spoil bench disposal would likely exceed existing groundwater quality and water quality criteria. Of the six potential "problem" parameters described in Section 6.5, only mangan- ese column leachate concentrations exceeded background groundwater quality. Minimizing Potential for Ground Water Contamination Trapper :fine's disposal plan for utility wastes will minimize the potential for ground water contamination to result. Since it is unlikely that contamination would occur from natural percolation and leaching, the primary concern of dis- posal will be to prevent contact of the waste body with ground water. As dis- cussed in Section 4.8.2, it is possible that the lower ends of the pits (north ends) will accumulate ground water with a resulting increased elevation of ground • water in those areas. Such sites are unsuitable for utility waste disposal with- out costly engineering controls. It is possible however, to anticipate a maximum 4-97 SE.P % 1992 7-8-82