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Mr. Daniel Heintz and Kristina Wynne <br />February 10, 2014 <br />DEPLETIONS <br />Page 2 <br />During this plan year, the maximum exposed surface area total of 17.2 acres within the <br />Active Pit (167 exposed acres) and the Unused Wash Pond (0.5 acres). You have submitted <br />an analysis that shows the calculated evaporation, effective precipitation, and resultant net <br />replacement obligation in the attached Tables 1 and 2. You have also performed a depletion <br />analysis based upon the net replacement obligation and the aquifer characteristics to show the <br />lagged depletion schedule to the Arkansas River, as presented in that attached Table 3. The <br />total lagged depletions for this plan year are estimated to be 59.88 acre -feet (57.91 acre -feet <br />from the Active Pit, 1.67 acre -feet from the Unused Wash Pond, and 0.3 acre -foot from the <br />sanitary/miscellaneous well). During the April 1, 2014 through March 31, 2015 plan year, the <br />site excavations will not expose any additional ground water. No mining or dewatering will take <br />place during this plan year unless an amendment to this plan is approved. <br />Stream depletion analyses for both the Active Pit area and the Unused Wash Pond <br />(attached) used the Stream Depletion Factors of 7.3 days for the Active Pit and 120 days for the <br />Unused Wash Pond, obtained from the USGS Publication 72 -192 "Stream Depletion Factors, <br />Arkansas River Valley, Southeastern Colorado ". <br />REPLACEMENTS <br />The source of replacement water is the Arkansas Groundwater Users Association <br />( "AGUA "), and the 1 -year lease agreement covering this plan year. The amount of the lease <br />water is for 61 acre -feet of fully consumable water. This volume of water will be delivered to a <br />point on the Arkansas River in Section 34, Township 20 South, Range 63 West of the 6`h P M <br />which is directly adjacent to the Rich Pit; therefore, transit losses will not be assessed. The <br />lease with AGUA will provide sufficient replacement water for depletions at the Rich Pit over the <br />plan year, and will be delivered according to the schedule outlined in Column E of the attached <br />Table 3. MMM is currently working with AGUA to finalize a lease agreement. A new lease <br />agreement must be provided for any renewal of this SWSP in the coming years. <br />In accordance with the letter dated April 30, 2010 from the Colorado Division of <br />Reclamation, Mining, and Safety ( "DRMS "), all sand and gravel mining operators must <br />comply with the requirements of the Colorado Reclamation Act and the Mineral Rules <br />and Regulations for the protection of water resources. The April 30, 2010 letter from <br />DRMS requires that you provide information to DRMS to demonstrate you can replace, or <br />provide bonding for an alternative method to mitigate, the long term injurious stream <br />depletions that result from mining related exposure of ground water. <br />A source of renewable long -term replacement water sufficient to cover <br />evaporative depletions has not been secured for this plan. At this time Martin Marietta <br />plans to proceed with the option to mitigate log -term injurious stream depletions that <br />result from mining - related exposure of groundwater according to the original plan <br />submitted by LaFarge to install a slurry wall liner for use as water storage for lining <br />and /or backfilling the pit. The Rich Pit was bonded for $51,542 with the DRMS, and has <br />recently increased the bond by $344,500 to cover the cost of the remediation (Bond No. <br />44284559, copy enclosed with application). <br />