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Battle Mountain Gold facility up the Rito Seco drainage on the west slope of the Sangre De <br />Cristo Mountains. Other activities that might be potential sources of contamination to the <br />ground-water resources of the Alamosa Formation aze not viewed by the locals at the same level <br />of concern. <br />The awning company currently monitors ground-water quality in a number of wells in <br />their project azea as well as a downgradient irrigation well on the Shalom Ranch. It is my <br />understanding that the municipal water supply is also sampled and tested by the mining company <br />on a limited basis. Based on discussions with staff of the Bureau of Mines and Geology, to this <br />point any impacts to ground-water quality have been con5ned to the Battle Mountain Gold <br />property. However, it was raised to my attention that a second irrigation well on the Shalom <br />Ranch property has been subject to deteriorating production due. to corrosive conditions in the <br />water. The source of this problem has not yet been identified. It is recommended that the <br />SLWSD contact with the CostiIla County Conservancy District (CCCD) for updates as this <br />problem is being further investigated. <br />RECOMMENDATIONS <br />Based on the analysis of information provided above, it is possible to recommend an area <br />for the installation of one or two monitoring wells as detection monitoring for protection of San <br />Luis' drinking water supply. The bigger issues involve the need far such a monitoring program <br />and the depth to which such sampling should be conducted at. <br />As stated above, at this time any impacts to ground-water quality from the Battle <br />Mountain Gold project seem to be limited to the permitted project property itself. There is a <br />distance of approximately 2.8 miles from the southwestern comer of the permit boundary to the <br />town's closest water-supply well. Estimating ground-water flow velocities based on conservative _ <br />assumptions for aquifer properties, it would take a contaminant plume from the site <br />approximately 15 years to reach the well via the ground-water pathway. However, this time <br />flame could be reduced if a release of contaminants to the Rito Seco drainage occurred. Under <br />this scenario, conraminants would be transported rapidly via surface-water flow and could seep. <br />into the shallow ground-water system over time and at points closer to the town'swater-supply <br />wells. Such a transport mechanism.would reduce the time for potential impacts to occur to less <br />than the estimated 15 years via the ground-water pathway alone but this combined migration <br />pathway is not realistically quantifiable. This discussion is offered for consideration in <br />determining the need for a detection monitoring effort by the SLWSD above and beyond what is <br />currently in place and undertaken by the mining company. <br />With this in mind if it is the SLWSD's decision to proceed with a detection monitoring <br />program for the longterm protection of their source water, a potential locational area is <br />recommended for one or more monitoring wells. Ttris azea would be at a relative point <br />intermediate between the irrigation well on the Shalom Ranch and the town's primary water- <br />supply well as well as at a relative point intermediate between the diversion of the Rito Seco to <br />Salazar Reservoir and the town's primary water-supply well. This general tocational area is <br />