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parameter Agency for same <br />notification. parameter. <br />Agency <br />notification. <br />The constituent list provided at the bottom of Table 3 and Table 4 was consolidated from analysis <br />of 15 quarters of operational data and 15 months of baseline data. Major cations and anions are included <br />for quality assurance/quality control of laboratory analytical work and for milli-equivalent ratio analysis <br />of water zone mixing. In addition to the ground water quality sampling and monitoring data, production <br />data is also a key element to determine what is likely to be present as a result of the mining activity. <br />American Soda has collected and analyzed samples from the collection points in the solution <br />mining streams at both the upper and lower well field production gathering lines and the injection stream <br />going into the wells on a monthly basis since commercial operations began. These data represent the <br />constituent concentrations of fluids that would be available to migrate into the overlying aquifers in the <br />event of a cavity breech or mining into a fault or fractured zone. The concentration of the constituents in <br />the solution mining brine shows some key iridicators that are markedly greater in concentration when . <br />compared to the various concentrations of these same constituents derived from the overlying aquifers. <br />In other words, it is expected that in the event of contact between the brine solution and the overlying <br />aquifers, analysis of these indicator parameters in the ground water system would show evidence and <br />extent of contamination from brine solution as a result of the comparative concentration differences. <br />As monitoring proceeds, the analysis of monitoring data may indicate that further changes to the <br />Water Monitoring Plan are warranted. To allow EPA and American Soda the best opportunity to adapt <br />the monitoring requirements to respond to future monitoring needs and conditions that maybe <br />encountered in the field, American Soda has requested that EPA allow for future modification of the <br />Water Monitoring Plan as a minor modification to the Permit. Specific changes to the monitoring plan <br />that would be accomplished as a minor modification to the Permit would occur only after a review of <br />monitoring data and an assessment the ongoing monitoring needs. Such changes could include: <br />• specific monitoring parameter changes, including the addition, deletion, or substitution of <br />specific parameters <br />• changes to sampling methods that would improve the ability to consistently and reliably <br />obtain representative samples <br />• changes to laboratory analytical methods that would improve the accuracy, reliability, or <br />comparative value of the results <br />• changes to the frequency of.monitoring, including an increase or decrease in the frequency <br />of monitoring at any or all monitoring locations <br />• modifications to the location of monitoring points, including the addition, deletion, or <br />substitution of specific monitoring wells or well completion zones <br />Reduction of the current monitoring requirements would be made only after a review of the data <br />demonstrates that the current monitoring requirements are: <br />1) redundant <br />For example, where other monitoring locations or data already provide adequate <br />monitoring coverage, a reduction in monitoring could be appropriate. <br />2) not producing reasonable data quality or quantity <br />FINAL Addendum to SOB For Modification No. 9, UIC Area Permit No. C030858-00000 Page 23 of 29 <br />