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.~ <br />7.0 RECOMMENDED GROOND-WATER MONITORING FREQOENCY <br />Some ground-water levels associated with Trapper Mine aquifers <br />vary significantly during the year. Water levels are being <br />measured quarterly to adeq~iately define these variations. The <br />annual air lifting of well GB1 affects the static water level in <br />this low permeability well for several quarters. Water levels <br />should be more indicative of the aquifer"s level without air <br />lifting. <br />Water quality associated with Trapper Mine aquifers does not <br />change very fast due to the small rates of ground-water movement. <br />The small permeabilities of these aquifers result in relatively low <br />rates of ground water movement. Therefore the late Spring and <br />• early Fall monitoring for water quality as approved and initiated <br />in 1991 should be adequate to define the water quality changes near <br />Trapper Mine. The ash and GLUX-1 wells are sampled quarterly due <br />to a smaller data base on these wells. Continued consistency in <br />analytical results should initiate a request by Trapper to reduce <br />sampling frequencies associated with ash monitoring and GLUX-1 <br />well. Changes from the CMLRD approved 1991 ground-water monitoring <br />program are not presently rer_ommended, except for the dropping of <br />the annual air lifting of well GB1, switching to replacement well <br />GD1 (2) instead of well GD1 and ceasing measurement of field <br />bicarbonate during the annual sampling. Field bicarbonate data is <br />not used in our annual analysis and, therefore, does not warrant <br />• the time required for this measurement. <br />7-1 <br />