Laserfiche WebLink
Nix Site Groundwater Contamination Potential <br /> March 31, 2023 <br /> mobilized from these sites could migrate toward the monitoring wells surrounding the Nix <br /> Site. <br /> With respect to potential sources of contaminants, any stormwater discharges will be made <br /> under a NPDES discharge permit from CDPHE and the site will be operated in accordance <br /> with a stormwater management plan (SWMP) that will ensure limited impacts to water <br /> quality from stormwater discharge.Although no hazardous chemicals are used in the <br /> proposed site operations or processing,fuel or other fluids used in the mining equipment <br /> could be one potential source of chemical contaminates. These risks are inherent with any <br /> operation utilizing heavy equipment and fuel storage but are not enhanced at the Nix Site <br /> compared to other operations that do not require such groundwater monitoring. For <br /> example,the excavation to install a slurry wall around a site, or farming operations have <br /> similar potentials to introduce these contaminates but generally do not require strict <br /> monitoring of the groundwater in the area. Even though the risk of spill is small,the site <br /> will have a spill prevention, control, and countermeasure (SPCC) plan in effect at all times, <br /> ensuring that any potential spills are adequately addressed. <br /> If contaminants were somehow introduced into Cell 1 it is unlikely they would be <br /> introduced in sufficient volumes to cause a potential threat to the public health,safety, or <br /> welfare,particularly given the lack of domestic, municipal, or agricultural use of the <br /> groundwater downgradient of the Nix Site. Utilizing the GIS database of well permits <br /> provided through CDSS,we looked at wells located in the vicinity of the Nix Site. For wells <br /> that potentially provide drinking water,we looked at wells with permitted uses including <br /> household use only, domestic, commercial, or municipal. For agricultural wells,we looked <br /> at wells with permitted uses of stock or irrigation. Figure 4 shows that there are no wells <br /> that potentially provide drinking water located downgradient of the either the unlined <br /> pond areas or the proposed slurry walls.While Figure 4 does show two agricultural wells <br /> downgradient, one well,located in the permit boundary of an adjacent mine site,is no <br /> longer used for irrigation and the other is a small stock watering well that is nearer to Saint <br /> Vrain Creek and relatively far downgradient of the Nix site. This stock watering well is also <br /> within the permit boundary of the M1999-006 site, although it does appear that the area is <br /> yet to be mined and any potential contamination from the Nix Site would be heavily diluted <br /> prior to reaching this well. The unlined portions of the M 1999-006 mine site,which has no <br /> monitoring requirements,would have a significantly higher risk of impacting this well than <br /> would the Nix Site and the M2015-033 site would present similar concerns but also has no <br /> monitoring requirements. Additionally,because most of the area downgradient of the Nix <br /> Site is covered by current and future gravel pits or is within the floodplain of Saint Vrain <br /> Creek, future development of the groundwater in the area is likely to be limited. <br /> DINATALE WATER CONSULTANTS 6 <br />