REV104845

• Permit No: C1981041
• IBM Index Class Name: Revision
• Doc Date: 3/7/1997
• Doc Name: MEMO ROADSIDE PORTALS PN C-81-041
• From: DMG
• To: ERICA CROSBY
• Type & Sequence: TR22
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Depanmenl of Natural Resources
1713 Sherman SL, Room 215 `y

Denver, Colorado 80203 ~
~~

Phone: [phone] II
FAX: [phone]
DEPARTMENT OF
NATURAL
interoffice
RESOURCES
MEMORANDUM
Ray Romer
Governor
lames 5. Lochhead

to: Erica Crosby Erecuvve Director
Michael B. Long

~
~'
' W Drv~sion Director
from: Byr
L+
i
alker ,
subject: Roadside Portal Mine (C-81-041)
date: March 7, 1997
Reference: Interoffice Memorandum, Crosby to Hernandez, March 6, 1997, Subject: Roadside
Portal Mine (C-81-041).
The purpose of this interoffice memorandum is to report on my review of the designs of Pond #
12 embankment. The report is limited to embankment stability, and does not include other
aspects of Sediment Pond #12 design. With regard to design criteria of Rule 4.06.6(11)
(a) the design meets this requirement (a specification).
(b) the design meets this requirement (a specification).
(c) the design meets this requirement (a specification).
(d)
(e)
(~
(g)
(h)
the design meets this requirement (a specification).
the design meets this requirement (profile).
the design meets (qualified) this requirement. The combined upstream and downstream
side slopes aze 6h:ly, less steep than [he criteria of Sh:ly. The upstream and downstream
side slopes are designed at 3h:ly, less steep than the criteria of 2h:ly (profile). No cross-
section of the east (existing) embankment is provided in the design.
the design (plan, profile or specification) does not meet this requirement.
the design meets this requirement (plan and profile). The top width of 8 feet is at the
minimum width required by the Rule [8.02 feet, (6 + 35)/5, the 6 measured off cross-
section A-A' as no ground elevation (upstream toe) was provided].
(i) does not apply. The height of the embankment from the bottom of the channel to the
bottom of the spillway is 4.6 feet (assumed ground elevation 4798), less than the 10 feet of the
criteria. The water surface area at high waterline (primary spillway) is 2.1 acre feet (SEDCAD+
measure of the plan), less than the 20 acres of the criteria. The volume of the pond (SEDCAD+
measure of the plan) is 6.26 acre fee[, less than [he 20 acre feet of the criteria.
(j) does not apply. The impounding structure can impound water sediment, or slurry to an
elevation of 4.2 feet above the upstream toe, less than the 5-foot criteria of CFR