2010-05-10_REVISION - M1977208

• Permit No: M1977208
• IBM Index Class Name: REVISION
• Doc Date: 5/10/2010
• Doc Name: 1st Quarter 2010 Monitoring Data
• From: CEMEX
• To: DRMS
• Type & Sequence: TR10
• Email Name: ACS
• Media Type: D
• Archive: No

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'MAY 10 2010
Div"n of r?zciam
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fv IAinhV and Safety
April 30, 2010
Mr. Allen Sorenson
Environmental Protection Specialist
Division of Reclamation, Mining and Safety
1313 Sherman Street, Room 215
Denver, Colorado 80203
Via Certified Mail 7007 2680 0001 6295 9914
Return Receipt Requested
Re: CEMEX Lyons Mine Permit M-1977-208
Technical Revision No. 10, C-Pit Hydrogeologic Investigations
/1 st Quarter 2010 Monitoring Data
Dear Mr. Sorenson:
In keeping with the requirements of Technical Revision No. 9 to Permit No. M-1977-208, this
letter transmits surface water and groundwater data from sampling the C-Pit pond and related
wells for the first quarter 2010. In TR9, we agreed to conduct five consecutive quarters of
sampling, beginning in fourth quarter 2007 and a re-evaluation of monitoring parameters at that
time.
There are two potential formations of concern in the area; the Fort Hayes and the St. Vrain
Alluvium. Monitoring in the Fort Hayes was conducted at compliance well CEM-005. As
CEM-005, the compliance well located in the Fort Hayes collapsed, there is not a monitoring
point associated with that formation. Previous groundwater modeling and subsequent monitoring
demonstrated that there is not impact or likely interaction with the Fort Hayes formation. Thus,
were are proposing no more monitoring in the Fort Hayes formation.
We are contracting Brown and Caldwell to review the existing monitoring information and
recommend the appropriate future monitoring associated with the St. Vrain formation. Alan
Notary may be contacting you on our behalf. Continued monitoring and observations indicate
that no additional seeps or springs down gradient of C-Pit are occurring. As agreed upon in TR-
9, we will continue to monitor for the presence of seeps or springs. On March 18, 2010, CEMEX
personnel sampled the water in the pool at the north end of C-Pit, and alluvial well, CEM-004.
CEMEX also monitored the water elevation in C-Pit and several piezometers. Please refer to the
text, figures, and appendices of the C-Pit Hydrogeologic Investigations report (Brown and
Caldwell, August 31, 2007) for site details, well construction, and related historical information.
The C-Pit pond water and groundwater samples taken were analyzed for pH, chloride, sulfate,
dissolved solids, dissolved selenium and dissolved thallium. Table 1 summarizes the results and
the prior quarterly sampling results for 2009. Samples were analyzed immediately for pH; that
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