HYDRO29532

• Permit No: M1977208
• IBM Index Class Name: Hydrology
• Doc Date: 10/4/2004
• Doc Name: Proposed Mitigation Plan
• From: DMG
• To: CEMEX Inc.
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
October 4, 2004
COLORADO
D [VISION O F
MIN SRALS
GEOLOGY
RE CLAMATION•MININO
SAFETY•SCIENCE
Mr. John Lohr ~ Bill Owens
CEMEX Governor
Russell George
P.O. BOX $29 Executive Director
Lyons, CO 80540 Ronald w. cottony
Division Director
RE: CEMEX, Inc., Lyons Mine, Permit No. M-1 77-208 Natural Resource Trustee
Proposed Mitigation Plan v
Deaz Mr. Lohr,
The Division received the proposed mitigafion plan for issues related to water quality in the C-Pit of the
Lyons Mine, Permit No. M-1977-208. Based on CEMEX's letter and the meeting between DMG,
CEMEX and Banks & Gesso on September 24, 2004, the Division has the following comments:
Wildlife Assessment
The Division forwazded the Wildlife Assessment Report to the DOW and USFS for comment. The
Division will forwazd any commentstsuggestions that are received to CEMEX. However, during the
meeting the Division suggested that CEMEX develop a daily monitoring program to note the presence of
birds andlor wildlife in the vicinity of the pond. Frequency and reporting will be addressed once
comments are received by the DOW or USFS.
SamDline. Analysis and Reporting
CEMEX proposes to monitor Selenium, Chloride, Sulfate, pH and Total Dissolved Solids twice monthly
in the C and A pits and laboratory results will be forwazded to the Division within 10 days of receipt.
Technical Revision O1 (TR-Ol) required that Thallium (T'1) be measured in the C and A Pits. CEMEX is
required to monitor for Thallium until the Division approves removal of this pazameter in the form of a
revision to the permit. Until such revision is approved to eliminate this pazameter, CEMEX will need to
continue monitoring Thallium in the C and A pits.
The Division request that CEMEX also monitor the water level in the C-pit, and report the levels to the
Division in the same fashion as noted above.
CEMEX proposes monitoring the Dakota well with the same pazameters noted above on a quarterly
basis. Please be aware that the Division has not approved the location of the Dakota well as suitable
location to monitor groundwater. In addition, the Dakota well is a private well, which would limit the
Division's access to the site. CEMEX will need to address these issues before the Dakota well can be
considered the groundwater monitoring compliance point for the C-pit.
CEMEX proposes to sample the Boulder Feeder Canal and the St. Vrain River to establish a water
quality baseline upgradient of C-Pit. CEMEX proposes 6 biweekly samples to establish a water quality
baseline. In order to obtain a representative baseline of the seasonal fluctuations CEMEX should obtain
5 quarters of baseline data to measure over a full yeaz.
Office of Office of Colorado
Mined Land Reclamation Active and Inactive Mines Geological Survey