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STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303)8663567 <br />FAX: (303) 832-0106 <br />Date: December 19, 2005 <br />To: Erica Crosby <br />From: Harry Posey ~=~`,-~ ~2~`"' <br />RE: Review: TR-06; Cemex Inc., Lyons Quarry; M-1977-208 <br />COLORADO <br />DIVISION O F <br />MIN~RALS <br />GEOLOGY <br />REC LANATION•NINING <br />SAf ETY•SCIFNGE <br />gill Owens <br />GOVeffbf <br />Russell George <br />Ezeoutive Dinxtor <br />Ronald W. cuany <br />Division Dinxtor <br />Natural Resource Trustee <br />The technical revision submitted December 2, 2005, appears adequate to initiate necessary <br />changes to lower the water level and reduce the exposed area of C-Pit. C-pit has been <br />problematic because of elevated selenium and high pH (pH = 12), which are of potential <br />concern to wildlife including but not necessarily limited to Rock Doves (common pigeons). <br />There are no provisions in the submittal to address pH, if necessary, in the residual pit water: <br />only selenium. The plan should also address pH. Furthermore, monitoring for other potential <br />contaminants should continue. <br />Because the configuration of the pit floor is not known, the operator has proposed to lower the <br />water level then re-assess the need to further minimize the potential contact area. To the extent <br />that the pit water may remain open to wildlife, the Division may need to make clear that it is the <br />surface area of the residual pond water, not the depth or volume of water, that is most <br />significant. <br />Cc: Carl Mount <br />Office of Office of Colorado <br />Mined Land Reclamation Active and Inactive Mines Geological Survey <br />