2005-04-22_REVISION - M2000016

• Permit No: M2000016
• IBM Index Class Name: REVISION
• Doc Date: 4/22/2005
• Doc Name: Adequacy Review no. 2
• From: DMG
• To: Lafarge West Inc
• Type & Sequence: AM1
• Media Type: D
• Archive: No

INTEROFFICE MEMORANDUM
COLORADO DIVISION OF MINERALS AND GEOLOGY
1313 Sherman St., Rm. Z15
Denver, CO 80203
To: Gregg R. Squire
FROM: Kathleen L. Sullivan, P.E.
SusJECr: M-2000-016, Lafarge West, Inc.: Riverbend Operation, AM-Ot
DATE: April 22, 2005
CC: Carl Mount, DMG (via e-mail); Kate Pickford, DMG (via a-mail)
This memo contains adequacy review comments to the applicant's March 14, 2005
adequacy response to the Division's hydrology and slope stability review of the Lafarge
West, Inc.: Riverbend Operation 112(c) Amendment (AM-01) Application, File No. M-2000-
016. These comments primarily relate to hydrology. A comprehensive review of the
geotechnical information submitted will follow.
In the following, "Memo Item" refers to the first adequacy review memo dated February 11,
2005. I have directed my comments to the applicant. The applicant may contact me with
any questions at [phone].
Rule 6.4.4 EXHIBIT D -Mining Plan
In the applicant's adequacy response to Memo Item 4, the applicant stated that the
requested details and engineering analyses regarding ditch capacity with respect to
dewatering and storm water runoff discharges to the various irrigation company ditches
"will be calculated during agreement negotiations'" and that "the Ditch Company will
determine what is acceptable in the agreement." The applicant also stated, "...impacts
[of discharges] to Big Dry Creek will be assessed during Lupton Bottom agreement
negotiations."
In order to approve this amendment allowing discharge to the irrigation company ditches,
the Division needs executed agreements with the ditch companies and/or engineering
analyses demonstrating each structure can accommodate the increased loading. An
engineering analysis of the impacts of proposed discharges to Big Dry Creek must also
be provided.
2. In responding to Memo Item 4's request for factors determining where water will be
discharged, the applicant stated, "In general, the dewatering water placed in the ditches
and/or waterways is only the water removed from that source ° Please explain this
statement.
3. Memo Item 4: The applicant also states, "Lafarge will not discharge more water than a
ditch, stream, or river can accommodate; all dewatering discharges will be assessed,
monitored, and modified as necessary during operations." What will the bases be for
determining what each type of watervvay can "accommodate" and how will the