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~°J Gf S C' ~/~' w/ v/ <br />CIVIL RES"~U RCES, LLC <br />ENGINEERS Q PLANNERS <br />May 11, 2006 <br />Mr. Tom Schreiner <br />Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />MAY f 22006 <br />,pryisiea of Miperala aad Geology <br />RE: Hall-Irwin Corporation, Application No. M-2006.003 ~~ <br />ParkerlDersham Sand and Gravel Resource; May 8, 2006 GroundwateF Model Review <br />Addendum 1 <br />Dear Mr. Tom Schreiner: - - <br />Following is Civl Resources' (Hall-Irwin Consultant) response to your Adequacy Review dated May 8, 2006, <br />Groundwater Model Review, °Parker-Dersham Gravel Mine° Hall-Irwin Corporation File M-2006-003, Class: Permit <br />The applicant must commit to determination of a baseline water level (elevation) for each of the six <br />(6) piezometers, submittal of such data to DMG prior to exposure of groundwater at the site, and <br />keeping a record of these baseline elevations on site for comparison during all future water <br />monitoring, ie: personnel recording groundwater levels in the piezometers during future <br />monitoring will need to have the baseline elevation established and available for comparison at the <br />time of monitoring to determine if an exceedance (3' or greater difference) has occurred. <br />Hall-Irwin commits to determining a baseline water level for each of the six piezometers and has obtained <br />approximately 18 months of baseline groundwater data at the locations shown in the Groundwater Study. <br />These six piezometers will also be used to determine future groundwater elevations and will be measured <br />throughout the life of the mine unless otherwise approved by the DMG. Civil Resources has provided Hall- <br />Irwinwith acopy ofthe Groundwater Study and Hall-Irwin will be able to use the study as a tool for <br />comparing piezometer elevations. <br />The applicant must commit to submittal of each years water monitoring data and summary of <br />resultsldiscussion in each years Annual Report. <br />Hall-Irwin will submit a report generated by qualified personnel or consultants summarizing the <br />groundwater measurements and mining operations affecting the site and regional groundwater, i.e. <br />dewatering, slurry lining, recharging if necessary. The report will be generated annually and submitted to <br />DMG unless otherwise requested or required per a response to a trigger. <br />The applicant must commit to reporting an exceedance of a groundwater elevation (3' or more) to <br />DMG within 24 hours of recording such measurement, and submittal of a technical revision <br />indicating the mitigation method employed within 30 days of verifying a exceedance of a <br />groundwater elevation. (The applicant may also want to re-measure the groundwater elevation <br />within 24 hours to confirm that an exceedance has occurred, then notify DMG within 24 hours of <br />the confirmed exceedance). <br />451 OAK STREET, SUITE 209 • FREDERICK, COLORADO 80530 • PHONE: 303.833.1416 • FAX: 303.833.2850 <br />