HYDRO29618

• Permit No: M2004078
• IBM Index Class Name: Hydrology
• Doc Date: 9/26/2007
• Doc Name: Groundwater quality monitoring results
• From: Civil Resources, LLC
• To: DRMS
• Permit Index Doc Type: Correspondence
• Media Type: D
• Archive: No

/) CIVIL RES~URCES,LLC
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.~.+ F_NQNEE125 8 PLANNERS
September 25, 2007 RECEIVED
Mr. Tom Schreiner ~EP 2 6 2007
Division of Reclamation and Mining Safety / ~, Division of Reclamation,
1313 Sherman Street, Room 215 7-a Mining and Safety
Denver, Colorado 80203
RE: July 2007 Groundwater Quality Monif ring Results, Lupton Lakes Gravel Mine
Permit No. M-2004-078
Dear Mr. Schreiner:
The following letter report describes the results from the Ju1y2007Sampling 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. Dewatering began in the area of the south sediment pond near Weld County Road 6
in June.
Groundwater Monitoring Results
The July 2007 Sampling Event includes monitoring wells CRMW01, CRMW02, CRMW04, CRMW06,
CRMW09, CRMW16, and CRMW41. The July monitoring event also included sampling at the two recharge
areas denoted as the South and North Recharge samples, respectively. The dewatering volume being
pumped from the south sediment pond area was recharged back to the natural alluvium aquifer instead of
direct discharge to the river. Refer to the attached figure for approximate locations of the recharge areas.
Following is a listing of the major results and conclusions:
• Fluoride did not exceed the PDWS or the proposed baseline levels in all wells tested.
Nitrate (as N) exceeded PDWS in five of the seven wells sampled with nitrate concentration levels
ranging from less than 0.4 up to 37.67 my/L in CRMW01. The PDWS for nitrate is 10 mg/L. The
currently proposed site wide baseline level for nitrate is 29.9 my/L. Two of the five wells that
exceeded the PDWS standard also exceeded the proposed baseline level for Nitrate including:
CRMW01 (37.67 mg/L) and CRMW02 (35.07 mg/L). However, considering that the site wells have
historically had similar levels and the added fact that very limited mining activity has been completed
on the north end of the site 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. The Recharge Area samples
contained approximately 16 to 17 mg/L consistent with typical levels in the area.
• Secondary Drinking Water Standards (SDWS) were exceeded for Total Dissolved Solids (TDS) (540
to 1,216 mg/L) consistently across the site. Sulfate concentrations slightly exceeded the SDWS in
wells CRMW02 and CRMW09 respectively. The remaining SDWS parameters tested for including
pH and Iron did not exceed the SDWS. Additional parameter test results and the summary of all
laboratory analysis results are contained in the attached table.
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