Laserfiche WebLink
Blue Earth Solutions described subsurface conditions using available data at the time of the <br /> report. The mine site has two to three feet thick silty to sandy clay overburden. The target <br /> gravel reserve, the alluvial material, is 30-35 feet thick. The groundwater saturated <br /> thickness ranges from 23 to 27 feet, with greater thickness approaching the river. <br /> Description of the Monitoring Program <br /> The Pueblo East Pit groundwater program is at a challenging point. Monitoring programs <br /> are typically comprised of a baseline study to identify ambient conditions followed by <br /> monitoring during the operation. This scenario allows pre-operation hydrologic <br /> characterization which aids in determining operation impacts. At Pueblo East Pit, baseline <br /> data is not available and the mine has operated, including dewatering, for more than ten <br /> years. Separating mine and non-mining impacts to the groundwater table will be difficult. <br /> Six monitoring points are proposed and located on Figure 1. Monitoring points #2 and #6 <br /> are located outside the dewatering radius of influence. Monitoring points #1 and #3 are <br /> upgradient of current mining activity. Monitoring points #4 and #5 are downgradient of <br /> current mining activity. Monitoring hole completion information available from DWR is <br /> provided in Table 1. <br /> Groundwater data collected during the first two years of the program will be evaluated in <br /> conjunction with historic data to characterize area groundwater. Monitoring will occur <br /> monthly for the first two years. Because baseline data is not available and with the mine's <br /> continued dewatering, preliminary data may identify environmental and other anthropogenic <br /> influences on groundwater levels but will not reveal dewatering influences. Historic <br /> groundwater data is available from well completion reports filed with Division of Water <br /> Resources and from the Blue Earth Solutions report. Historic Arkansas River flow data and <br /> area weather data will also be considered. Vicinity conditions that will also be monitored <br /> will include irrigation activity, Excelsior Ditch activity, Arkansas River flow rates, <br /> precipitation events and dewatering pump rates. <br /> Monitoring subsequent to the initial two years will depend on mining activities. <br /> Groundwater monitoring will be performed quarterly subsequent to the initial two-year <br /> period as long as dewatering continues. In the event dewatering ceases, monitoring will be <br /> increased to bi-weekly, being performed by the responsible party. <br /> Monitoring will be limited to field parameters and area observations. Groundwater level will <br /> be measured water level meter. After purging the well, pH, temperature and electrical <br /> conductivity will be measured with a handled meter. The handled meter will be calibrated <br /> prior to each monitoring event. <br /> Without a baseline study, groundwater data interpretation will be limited to comparisons of <br /> conditions. After the first two years of data collection, parameter influences may be <br /> identified. Supportable comparisons that would indicate cause and effect may require up to <br /> five years of data collection. <br /> Please feel free to call me directly with any questions at 719-275-8951. <br /> Respectfully submitted, <br /> Angela Bellant ni Ph.D. [qV rr(ogMegIL <br /> ILEda Itc ce:�rrnaLc11\�1e� 11 nq C. <br /> 1107 Main Street, Canon City, CO 81212 <br /> www.envalternatives.com • e-mail: eai@bresnan.net <br /> Phone: 719-275-8951 • Fax: 719-275-1715 <br />