2011-02-24_REVISION - C1981019

• Permit No: C1981019
• IBM Index Class Name: Revision
• Doc Date: 2/24/2011
• Doc Name: Preliminary Adequacy Review ‎(Memo)‎
• From: Marcia Talvitie
• To: Janet Binns
• Type & Sequence: PR3
• Email Name: JHB
• Email Name: MLT
• Email Name: SB1
• Media Type: D
• Archive: No

DIVISION OF RECLAMATION, MINING AND SAFETY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone] INTEROFFICE MEMORANDUM
Date: 24 February 2011
To: Janet Binns, Lead Specialist
From: Marcia L. Talvitie, P.E.
MINING
SAFETY
John W. Hickenlooper
Governor
Mike King
Executive Director
Loretta E. Piheda
Subject: Colowyo Mine — Permit No. C-1981-019 PR-03 Director
Preliminary Adequacy Review — Engineering/Geotech
As requested, I have conducted a review of the PR-03 application for the Collura area at the
Colowyo Coal Mine. My review focused on the engineering and geotechnical aspects,
spec ically the haul and access roads and the temporary excess spoil pile. It is my
understanding (via communication from Dan Hernandez) that the mine plan for the Little Collura
X Pit will be substantially modified in the near future. Given the associated changes that may
occur, my comments are in some cases more general than specific.
Rule 2.05.3(3) and 4.03 Haul Roads and Access Roads
A set of three (West, Central, and East) haul roads are proposed to connect the Collum
Lite area with the proposed excess spoil pile. The roads are illustrated on Map 25D, and
described on Rule 2, Page 94 and Rule 4, Page 2.
a. Map 25D shows one site-specific cross section for each of the haul roads (at Sta.
25+00). However, no Typical Section has been provided. Please insert a "typical
section" on Map 25D, at an appropriate scale, which illustrates the roadway width
ad cross slope, ditch dimensions, and proposed slopes for both cut and fill
situations.
b. Note 10 of the Design and Construction Notes on Map 25D addresses the
requirements of road embankments [per 4.03.1(3)(e)]. The text here should be
modified to include specific language addressing the requirements of (e)(ii)
regarding construction on slopes steeper than 20% (also, will this situation
occur?) and (e)(iv) which prohibits the use of acid-producing materials in
embankment construction. Please expand the information in Note 10 accordingly.
2. Another haul road (Collum Access Road) is proposed to provide access from the primary
crusher to the Gossard loadout facility. This road will be approximately 6 miles long; the
surface is divided between a 24' paved surface for vehicle use and a 73' gravel section
for the haul trucks. Details are provided on Map 25E, Sheets I — 9, and described on
Rule 2, pp 93-94 and Rule 4, Page 2. Construction Note 10 on Sheet 3 of Map 25E
addresses the requirements of road embankments [per 4.03.1(3)(e)]. Please revise the
text to include specific language addressing the requirements of (c)Oii) regarding
construction on slopes steeper than 20% (also, will this situation occur?) and (c)(1v)
which prohibits the use of acid-producing materials in embankment construction.
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Mined Land Reclamation Denver ® Grand junction ® Durango Active and Inactive Mines