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Mr. O'Brian—Environment Inc. <br /> March 27 <br /> Page 4 of 6 <br /> Exhibit G. After reviewing the provided information DRMS has the following comments and additional <br /> requirements. <br /> In the first paragraph of the"Mitigation Trigger" section,the last sentence states that mining will start in unlined <br /> areas,however Phases I and 2 are shown to be slurry wall lined, so this statement is a bit unclear. Please revise as <br /> needed. Please also acknowledge that DBMS requires a minimum of five quarters of groundwater level <br /> monitoring prior to dewatering or groundwater exposure at the site. <br /> Some nearby wells referred to in Table G-1 (Permits 195505, 38703, and 25007-F-R) are not shown on the <br /> provided figure for G-1 or Exhibit C existing conditions/structures. Please add these wells or explain why they <br /> aren't relevant. <br /> Please provide a table/figures showing all available water level monitoring data and trends over time for the <br /> monitoring wells listed. <br /> DRMS acknowledges the difficulty in establishing appropriate trigger levels for mitigation in a large area with <br /> numerous external influences and large seasonal variations. To help mitigate these issues,minimize the impacts <br /> to the hydrologic balance, and/or demonstrate that the permittee has successfully addressed any reported impacts, <br /> it is vital to determine what the existing"pre-mining"conditions are for nearby wells that may be impacted. <br /> Therefore,in addition to the required five quarters of pre-mining water level data,DBMS will also require the <br /> permittee to attempt to document background conditions in the seven alluvial wells within 200 feet of the site <br /> shown in Table G-1 prior to initiating dewatering activity associated with this permit. This data is especially <br /> important for this site,where mining activity may have the potential to adversely impact nearby alluvial wells. <br /> Wells shown on the provided map as owned by Bangert/Evans,Pacheco,and Castle Pines are all immediately <br /> adjacent to unlined mining areas, and are of particular concern/interest. For the seven listed shallow wells, <br /> DRMS will require that the permittee attempt to obtain the following data,in addition to whatever basic well <br /> construction data is currently available: <br /> Total well depth, <br /> Depth to static water level, <br /> Depth of pump intake <br /> Conduct pump test to determine well yield <br /> Conduct analytical sampling of all Domestic Drinking Water parameters <br /> All data collection will be completed at the permittee's expense. Data will be provided to DRMS and the well <br /> owner upon their request. If a well owner chooses not to allow the permittee access to collect the above data,they <br /> should be provided with a form that they can sign and date to document that they have been provided with an <br /> opportunity to have their well characterized at the permittee's expense,but have chosen to decline to participate. <br />