Laserfiche WebLink
<br /> <br />Memo to File M-77-215 -2- December 27. 1995 <br />otherwise) and Rat Creek/Miners Creek. Willow Creek has been <br />classified by the Water Quality Control Commission as "Existing <br />Quality" (segment 7 of the Rio Grande Basin), and Rat Creek/Miners <br />Creek are in segment 2 of the Rio Grande Basin, which has been <br />classified Aquatic Life Cold 1, Recreation 1, Water Supply, and <br />Agriculture. <br />3. It is DMG's view that neither "Domestic Use" nor "Surface Water <br />Quality Protection" can be ruled out as existing or potential future <br />beneficial uses of ground water down-gradient from the Bulldog Mine <br />surface tailing impoundments. "Agricultural Use" may also be an <br />existing or potential future beneficial use of ground water at the <br />site. Results of DMG's leachate analyses of tailing from both the <br />upper and lower impoundments indicate that discharges of leachate to <br />ground water may exceed drinking water and aquatic life numeric <br />protection levels for a number of parameters. DMG proposes that the <br />following measures be implemented in order to assess the potential <br />for impacts to ground water that may be caused by leachate from the <br />surface tailing impoundments: <br />a) HMC sampled a number of domestic supply wells in the vicinity <br />of the Bulldog Mine during 1981 and 1982. HMC should provide <br />information on the location of these wells, and should identify the <br />location of all potentially impacted wells, stock ponds, etc. down- <br />gradient from the surface tailing impoundments. <br />b) HMC should provide all available data, and their analysis of <br />the data, from the monitoring wells formerly associated with the <br />lower tailing impoundment. HMC should provide details and an <br />assessment of the effectiveness of the ground water flow barriers <br />installed at the lower tailing dam in preventing leachate from the <br />tailing from entering the local ground water system, or from <br />reaching potential ground water receptors. <br />c) Ambient ground water quality up-gradient and down-gradient of <br />both tailing impoundments needs to be characterized. In order to do <br />this, monitoring wells would have to be established, at a minimum, <br />in shallow ground water above and below the upper tailing <br />impoundment, and, depending on the usefulness of the available data, <br />above and below the lower tailing impoundment. If data from such <br />wells provides a satisfactory demonstration that ground water down- <br />gradient from the tailing impoundments is no more contaminated than <br />ground water up-gradient of the impoundments, or if contaminant <br />concentrations do not exceed the standards protective of existing or <br />potential future ground water uses, DMG would make a finding that <br />reclamation has been achieved such that existing and reasonably. <br />potential future uses of ground water are protected. if analysis of <br />data from the wells demonstrates that leachate from the tailing is' <br />impacting the local ground water system, HMC may be required to <br />monitor the wells for a period of time sufficient to demonstrate <br />