2009-10-23_REVISION - M1977208

• Permit No: M1977208
• IBM Index Class Name: REVISION
• Doc Date: 10/23/2009
• Doc Name: 3rd Quarter 2009 Monitoring Data
• From: CEMEX
• To: DRMS
• Type & Sequence: TR10
• Email Name: ACS
• Media Type: D
• Archive: No

AGMEX?
October 12, 2009

,/- - 3I--.

Mr. Allen Sorenson Via Certified Mail 7007 2680 0001 6365 9097
Environmental Protection Specialist Return Receipt Requested
Division of Reclamation, Mining and Safety
1313 Sherman Street, Room 215
Denver, Colorado 80203
Re: CEMEX Lyons Mine Permit M-1977-208
tWchnical Revision No. 10, C-Pit Hydrogeologic Investigations
3rd Quarter 2009 Monitoring Data
Dear Mr. Sorenson:
This letter transmits surface water and groundwater data from sampling the C-Pit pond and
related wells, in keeping with the requirements of Technical Revision No. 9 to Permit No. M-
1977-208.
On September 16, 2009, CEMEX sampled the water in the pool at the north end of C-Pit, as well
as groundwater from monitoring well CEM-001, the nearest well, and the alluvial well, CEM-
004. CEMEX also monitored the water elevation in C-Pit and in CEM-001. 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 information.
As mentioned'in prior reports, CEM-005 has collapsed. This item was verbally reported in
March 2009, in writing in the C-Pit Monitoring Report of April 6, 2009, and in our October 14,
2009 meeting. Based on the 1998 hydrologic model, the absence of water in CEM 005 prior to
collapse, and the lack of any other indicator, it is concluded that the migration of water and/or
any potential contaminants and from C-Pit to the Dakota Sandstone or Fort Hayes Limestone is
not expected. The agreement of TR-9 was to monitor water depth at CEM-005 on a semi-annual
basis, and in the event the well shows signs of increased water volume sufficient to sample, an
attempt be made to obtain a sample. Per our conversations, we do not have evidence to believe
the water present in the well at this time is from the Fort Hayes Limestone, and as such, have not
analyzed any samples. The water level is more representative of a localized perched water table.
We will be submitting a Technical Revision JR-11) under separate cover to remove this
provision from the existing monitoring plan.
The C-Pit pond water and groundwater samples taken on September 16 were analyzed for pH,
dissolved selenium, dissolved thallium, chloride, sulfate, dissolved solids, and specific
conductance. Table 1 summarizes the results, and the most recent analytical laboratory reports
are enclosed with this letter as an attachment.
United States Operations
P 0 Box 529, Lyons, CO 80540, USA, Phone [phone], Fax [phone]