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Joanna Williams <br /> March 12,2018 <br /> Page 4 <br /> • Stage 3 currently exposes 1.0 acre of ground water. Mining is completed at Stage 3 and <br /> the stage is anticipated to be backfilled by May of 2018 so as to reduce the exposed <br /> ground water surface area to %2 acre. Stage 3 will, in the future, be completely backfilled <br /> so as to eliminate exposed ground water. <br /> • Mining at Stage 6A is completed. It exposes 3.0 acres of ground water. <br /> • The projected maximum net evaporation volume during March 2018 through December <br /> 2018 is approximately 94.1 ac-ft, based on a maximum surface area of 36.5 acres within <br /> the mining boundary as shown in Table 2, column 2. This is a conservative projection <br /> since the maximum surface area of exposed ground will(a)not all be exposed at one time <br /> and (b) may be less than projected. Actual evaporation from exposed ground water will <br /> be accounted for and lagged based upon the actual exposed ground water area at each <br /> stage. <br /> Gravel Production <br /> In addition to evaporation, water is lost with the mined product removed from the mine. RMCC <br /> is projecting that they will produce 1,355,000 tons of gravel during the remainder of 2018, as <br /> shown in Table 2, column 3. The mining occurring during the requested 2018 amendment <br /> period will primarily occur at Stage 4. The slurry wall at Stage 4 has been completed, and the <br /> gravel mined will be in a dewatered state and will be washed. Therefore, the losses associated <br /> with production is limited to the 2 percent for wash water of the gravel production through 2018. <br /> The gravel production depletions are projected to total 19.9 ac-ft for the SWSP amendment for <br /> March through December 2018. <br /> Dust Suppression <br /> The use of water for dust suppression has been adjusted to reflect actual data confirming <br /> seasonal variation in volumetric needs (1.2 ac-ft/month for March-July, 1.0 ac-ft/month in <br /> August, 0.8 ac-ft/month for September-October and 0.5 ac-ft/month for November and <br /> December). <br /> Dewatering and Fill <br /> As described previously, RMCC will dewater Stages 6A, 3 (until it is backfilled) and 4 in order <br /> to mine the gravel. The northern 7-acre portion of Stage 1 was allowed to fill with water in June <br /> 2017 primarily during free river conditions. Stage 2 was filled during free river conditions in <br /> October and December 2017, resulting in a surface area of 7 acres. Stage 6B is planned to be <br /> partially filled in the Spring of 2018, as early as this week, dependent on free river conditions. <br />