PERMFILE102059

• Permit No: M2004078
• IBM Index Class Name: Permit File
• Doc Date: 3/24/2005
• Doc Name: Proposed Mine Slope Offsets
• From: Civil Resources LLC
• To: DMG
• Media Type: D
• Archive: No

CIVIL RES~URCES,LLC
ENGINEERS & PLANNERS
~~~'d~ED
March 22, 2005
MAR 14 ~
81Nf§l8ii 8(btiherels and Geology
Allen Sorenson
Department of Minerals and Geology
Department of Natural Resources
1313 Sherman Street, Room 215
Denver, Colorado 80203
Re: SW-TKO Joint Venture, LLC: Proposed Mine Slope Offsets; DMG#53.2 ~M1A -7.004 -O~' ~
Dear Mr. Sorenson:
As discussed in our meeting last March 1P^, 2005 with Erica Crosby, we've updated our mining plan to offer maximum
encroachments of the mining slope toe from nearby structures. Also, the shear strength of the alluvium and the
weathered claystone were lowered per your request to effective friction angles of 35° and 14° respectively. Additional
geotechnical data had been generated following the initial submission of the mining slope stability report and these data
are presented on Table 1.
Cross sections C-G, D-D, and E-E were run with the updated shear strengths ahd proposed affse-ts to evaluate an
appropriate maximum endroachment limit of the mining slope toe to the structure of interest. These three cross sections
represent maximum sections near Highway 85, WCR 27/Fulton Ditch Lateral, and WCR 6/WCR 8. i'fs: graphic results of
the three analyses are attached to this letter. The following maximum encroachment limits of the min:)g slope toe
(defined as the c(intact of the mining slope with the top of weathered bedrock) to the identified structl.~e is shown on
Table 2 below.
TABLE 2 -SLOPE STABILITY RESULTS AND SETBACKS
Section Critical Structure Modeled Surchar e, sf Max. Encroachment, ft Factor of Safet
C-C iii t'Ivra" 85 -- - -30G ' 100 - i. i6
D-D Fulton Lateral/WCR27 Irri ation rechar a/250 85 1.39
E-E WCR 6 and WCR 8 250 75 1.10
The following notes will be added to Exhibit 3 of 7:
1. The toe of the mine slope is defined as the contact of the mine slope with the top of weathered bedrock.
2. The maximum allowed encroachment of the mine slope toe with Highway 85 is 100 feet.
3. The maximum allowed encroachment of the mine slope toe with. the Fulton Lateral is 95 feet.
4. The maximum allowed encroachment of the mine slope toe to WCR 6 and WCR 8, within 1300 feet of Highway
85 is 75 feet:
5. The maximum allowed encroachment of the mine slope toe to WCR 6 and WCR 8, further than 1300 feet from
Highway 85 is 65 feet.
451 OAK STREET, SUITE 209 ~ P.O. Box 680 ~ FREDERICK, CO 90530 ~ 1303) 833-1416 ~ [phone] cAx