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Mc Gregg Squire October ]9, 2004 Page 1 of 4 Fuels and lubricants stored and/or used on site in association with the mining operation will be managed in accordance with applicable State and Federal regulations, including a Spill Prevention, Control and Countermeasures Plan (SPCC) developed and certified by a registered professional engineer. 'The SPCC provides-for appropriate containment and spill response measures. In addition, the mining activities operate in compliance with a Colorado Discharge Permitting System (CDPS) dischazge permit. The permit includes the continued updating and implementation of a site Stormwater Management Plan. The plan is designed to prevent the contact and transport of potential contaminants by stormwater flows. Both the SPCC and SWMP provide for regulaz inspections of general plant conditions, containment areas and facilities associated with the use or storage of fuels and lubricants. These plans aze updated as required to reflect changes in facilities or best management practices. 3. Exhibit G -Water Information As stated in Exhibit G, the mining operation will affect the alluvia] groundwater system hydrologically connected to the South Platte River. The mining operation will extract sand and gravel deposits from the saturated alluvium and the site reclamation will include construction of slurry walls within the alluvium. To anticipate and mitigate potential affects to the alluvial groundwater system, monitoring wells have been installed on the site and alluvial groundwater data have been collected for over two and a half years. The collected data were used along with site bore log infonnation, published studies and reports prepared by federal and State water resource agencies, and information from adjacent aggregate mining operations to prepare a site hydrostratigraphic summary report (see attached report).. The attached report summarizes alluvial groundwater conditions at the Wattenberg Lakes site and presents an interpretation of baseline conditions. The report also estimates alluvial characteristics (i.e. gradient, hydraulic conductivity) that will control the aquifers .response to mining and reclamation activities. Based upon the estimated alluvial characteristics, potential drawdown affects from dewatering of the three smaller mining areas were calculated in the report. Calculations to estimate the aquifer response to construction of the slurry walls were not performed. Given the aquifer chazacteristics on and -near the proposed project site (relatively high transmissivity and low gradient), major groundwater mounding and shadowing impacts from the slurry walls are not anticipated. The proposed reservoirs are separated by undisturbed alluvial material that will allow groundwater flow aoound the slurry walls. The shape and positioning of the reservoirs also minimizes the area of slurry wall perpendicular to the direction of groundwater flow, aiding natural flow around the reservoirs. It is expected that mounding and shadowing affects would be greatest immediately adjacent to the slurry walls, within the permit boundary. Because of the relatively low groundwater gradient across the site, only a couple of feet of groundwater mounding will push flows around the slurry walls at velocities similar to those estimated for baseline conditions. Similarly, groundwater gradients and flows will be quickly shifted towazds areas of shadowing. To continue to evaluate dewatering and sluny wall affects, the applicant commits to continue the monitoring of alluvial groundwater wells (see attached report}. The wells will be monitored on a monthly basis and results of the monitoring effort will be submitted to the Division along with other annual reporting requirements. With the baseline data already collected, consistently _". ,. . , .,_ . ~. ,, _, .... . I