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CIVIL RES7URCES,LLC ENGINEERS $ PLANNERS June 25, 2007 ~~~~~~~~ Mr. Tom Schreiner Division of Reclamation and Mining Safety rJUN ~ 81001 1313 Sherman Street, Room 215 Division of Reclamation Denver, Colorado 80203 Mining and Safety ' RE: April 2007 Groundwater Quality Monitoring Results, Lupton Lakes Gravel Mine Permit No. M•2004.078 Dear Mr, Schreiner The following letter report describes the results from the April 2007 Sampling Event. This report is being submitted in general compliance with approved Groundwater Sampling and Analysis Plan (GWSAP) included in Technical Revision 2 (TR2) to the Lupton Lakes Gravel Permit issued by the State of Colorado Division of Minerals and Geology. Monitoring wells CRMW01, CRMW02, CRMW04, CRMWO6, CRMW09, CRMW16, and CRMW41 were redeveloped prior to the sampling events to reduce the amount of sediment in these wells. There was no dewatering of the mine at the time of this sampling event. Groundwater Monrtorina Results The April 2007 Sampling Event includes monitoring wells CRMW O7, CRMW02, CRMW04, CRMW06, CRMW09, CRMW16, and CRMW41. Following is a listing of the major results and conclusions: Arsenic concentrations did not exceed the proposed baseline level for this site of 0.03 mglL. • Fecal Coliform was detected in three wells (CRMW01, CRMW04, and CRMW06) at a level of 2 mpn/100m1 in each well. The PDWS standard for fecal Coliform is no detection. Fecal Coliform was not detected in any of the other wells tested in this sampling event. The proposed baseline level for fecal Coliform concentration level is 1. Each of these exceedances occurred in wells located downgradient or cross gradient from inhabited structures vrith active septic systems. • Fluoride did not exceed the PDWS or the proposed baseline levels in all wells tested. • Mercury concentrations did not exceed the Primary Drinking Water Standards (PDWS), however the mercury concentration in CRMW04 exceeded the proposed baseline levels by 0.00007 mg/L. Nitrate (as N) exceeded PDWS in five of the seven wells sampled with nitrate concentration levels ranging from less than 0.04 up to 43.08 mg/L in CRMW02. The PDWS for nitrate is 10 mg/L. The proposed site wide baseline level for nitrate is 29.9 mg/L. Two of the five wells that exceeded the PDWS standard also exceeded the proposed baseline level for Nitrate including: CRMW02 (43.08 mg/L) and CRMW41 (31.34 mg/L). However, considering the very limited mining activity that had been completed at the date of this sampling event in the vicinity and upgradient of these wells and the fact that these wells are located at the north side of the site (1 mile away from the mining area), these exceedances are not attributable to mine activity and should be considered in reevaluating approved baseline levels in the area. 323 Flc'rti STREET • PD. Box 680 • FREDERICK, CO 00530 • PI-IaNE 1303) 833-141 6 • Rix (303) H33-2850