PERMFILE109268

• Permit No: M2001046
• IBM Index Class Name: Permit File
• Doc Date: 2/28/2002
• Doc Name: Review of Wright Water Engineers Reports
• From: Al Amundson
• To: Tony Waldron
• Media Type: D
• Archive: No

DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAR: [phone]
STATE OF COLORADO
Memo
DIVISION OF
MINERALS
GEOLOGY
RECLAMATION
MINING•SAFETY
To: Mr. Anthony Waldron February 28, 2002 Bill Owens
Goverrror
Greg E. Walther
From: AI Amundson Executive Director
Michael B. long
Divisi n Director
Subject: M-2001-04ti Nix Pit -Staff Review of "Evaluation of Potential Well-Impacts
From The Proposed Nix Property Sand And Gravel Operation" AND
"Evaluation Of Potential Impacts To Wetlands On The Sage Hill Farm From
The Proposed Sand And Gravel Operation" Prepared by Wright Water
Engineers for Owens Brothers Concrete.
Review of the subject reports has been conducted by the Division to determine the adequacy and
applicability of the reports. The reports appear to describe the groundwater levels adjacent to the
mine site and the location of the monitoring wells seems to yield a reasonable understanding of the
groundwater impacts that may affect the neighboring wells and wetlands.
In the first report, the last date for groundwater elevations is September 14, 2001 the four sets of
measurements indicate fluctuations, appazently as a result of irrigation, ranging from 0 to 3.65 feet.
The fluctuations do not seem to be similar in magnitude or direction.
In the Wetlands report, October 10, 2002 is the last date for sampling data. The additional sampling
date does not alter the magnitude of fluctuation. It seems the Operator would be well served to have
monthly data on water levels through the winter to determine the lowest ground water table elevation
to expect during their operation. This lowest level would likely be the basis for a trigger for
additional mitigative measures to prevent undue stress on the neighboring wells or wetlands. The
Division should be provided these data as soon as the are available.
Wright Water Engineers Mitigation Measures recommends the Operator mine Pit 3 in two steps with
a new berm constructed between them, as Pit 3A would be up gradient of the wetlands. This appears
to be a good idea, but it is confusing whether Pit 3 would be mined in advance of Pits 1 and 2. This
should be clarified and the new berm and the mining order specified in the latest adequacy reply.
Appazently, Banks and Gesso have taken the above mentioned recommendation by Wright Water
Engineers into account with the Exhibit C-3 Mine Plan Map -Revised, dated 2/12/02. It appears the
20 foot wide berms sepazating Mine Area 1 from Mine Area 3 and Mine Area 4 together with the
sequencing of the mining stages serves to accomplish the mitigative measure 1 from Wright Water
Engineers.