2005-02-01_REVISION - M1977129

• Permit No: M1977129
• IBM Index Class Name: Revision
• Doc Date: 2/1/2005
• Doc Name: Final Approval
• From: DMG
• To: Whitewater Building Materials
• Type & Sequence: TR2
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
731: Sherman SL, Room 215 C O L O RA D O
Dem~er, Colorado 80203 DIVISION O F
Phore: [phone] M I l~l & A L $
FAX: [phone] G E O L O G Y
' - REC L~NRTION•NINING
SAFETY•SQ ENCE
Bill Owens
DATE: January 28, 2~~5 Governor
Russell George
T0: Steve Shuey Executive Director
Ronald W. Cattany

FROM:
Allen Sorenson Division Director
Natal Resource rrGStee
RE: Review of As-Built Drawings, Stage Ilnlet/Outlet Channels, Whitewater Building
Materials Corporation, Whitewater Pit 500, Permit No. M-1977-129
The Division of Minerals and Geology (DMG) engineering staff has reviewed the design drawings
approved in technical revision TR-02 for the inlet and outlet channels• in the stage I pond perimeter and
the as-built drawings for these channels that were subsequently provided by the Operator..The purpose. .
of these channels is to allow flow from the adjacent Gunnison Riber.into and out of the pond during
high stream flows. The drawings designate these channels as U/S notch-for the upstream channel and
D/S notch for the downstream channel.
Based on the review of the drawings, DMG has determined that the channels were constructed in
general accordance with the approved plans and that the channels will function in accordance with the
intent of the design. The as-builts show some variances from the design plans. For example, the side
slopes of the notches were built at slopes much flatter than the 2.5:1 (typ.) slopes shown on the design
drawings, but this will actually result in greater channel stability. Also the channel bottom widths are
narrower than shown in the design, but because the channel side slopes are flatter the cross sectional
areas aze about the same and flow capacity will not be much diminished. Finally, the D/S notch invert
was constructed 1.25 feet higher than shown in the drawings; this will not appreciably impact the
operation of the channels or pond.
The only problem identified on the as-built drawings is a typographical error on drawing C-1 as-built,
where notch D/S is inadvertently labeled as notch U/S.
c;c: Carl Mount, DMG (via email)
c:`acs\LOANER MACHINEWiy Documents\whitewater as builts.doc
Office of Office of Colorado