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III IIIIIIIIIIIIIIII <br />999 <br />MEMO <br />Date: November 29, 2000 <br />From: Tom Kaldenbach ~ ~ ~~~ <br />To: Annual Hydrology Report File <br />Apex No. 2 Mine, Permit C-81-011 <br />Re: Evaluation of Apex Mine's potential for contaminating bedrock aquifers <br />I have evaluated the potential for water in the Apex No. 2 Mine workings to contaminate <br />bedrock aquifers. Apex has no bedrock monitoring wells, so, in the evaluation I relied on <br />information in the mining/reclamation permit and DMG's files. <br />This memo explains my conclusion that the Apex No. 2 Mine workings probably aze filling with <br />the water that se,~ps into the mine from bedrock in the floor, walls, and roof of the workings. <br />The water will probably fill the workings to a maximum elevation of about 7350 feet during the <br />next 30 years. Some of the water flowing into the workings is discharged out the northeastern, <br />down-dip end of'the workings into a sandstone bed in the basal Williams Fork aquifer. Mine <br />sump water quality reported in the permit indicates the dischazged water will not cause material <br />damage to the aquifer. <br />Evidence indicating inflow into the Aaex No. 2 Mine <br />The following six observations support a conclusion that the mine is probably filling with water. <br />1. Mine c/orkings in the Apex No. 2 Mine below elevation 7350 fr. produced a "very <br />limited. amount" of water (source: permit page 58). Mine water pumping during <br />mining, was not expected to be necessary (there is no record of pumping in the permit or <br />files).'fhe Division verified the description on permit page 58 during an inspection in <br />the mine workings on 6/2/82. <br />2. A sump in Apex No. 2 Mine in 1977 extended from elevation 7300 ft. to elevation 7315 <br />ft. (source: permit page 58). <br />3. A sump in the old Apex No. 1 Mine stabilized at about 7355 ft. (source: permit page <br />58). <br />4. No water was encountered during excavation of the mine workings through bedrock <br />and through faults (source: page 65.01 of permit). The Division verified the faults <br />were dry during an inspection in the mine workings on 6/2/82. <br />5. Geophysical logs (SP and bulk density logs) of drillholes in the permit azea (Exhibit III- <br />B and log copies in permit) indicate the Lower Pinnacle seam is bounded below and <br />above by shale and shaley sandstone (see attached interpreted log copy). There is no <br />Page 1 <br />