PERMFILE101415

• Permit No: M2004078
• IBM Index Class Name: Permit File
• Doc Date: 5/10/2005
• Doc Name: CDOPT Obj Ltr- Slope Stability
• From: Civil Resources LLC
• To: CDOT
• Media Type: D
• Archive: No

Mr. Joe Intermill
May 9, 2005
Page 2
TABLE 1: SUMMARY OF BULK SAMPLE GRADATIONS
SW TKO -Lupton Lakes Site
~~
CIVIL RES'JU RCES,LLC
Location Classification Gradation
Test
Pit Observed Top
of Aggregate,
ft Depth of
Sample, ft Gravel
(%) Sand
(%) Fines
(%) Percent
Passing US
#50 Sieve Percent
Passing US
#100 Sieve Percent
Passing US
#200 Sieve
TP 1 3 4 21.0 78.6 0.4 13.0 2.0 0.4
TP 2 4 5.5 33.0 64.0 3.0 11.0 4.0 3.0
TP 3 4 5.5 23.0 75.6 1.4 12.0 3.0 1.4
TP 4 3 6 25.0 74.4 0.6 7.0 1.0 0.6
TP 5 4 7 38.0 45.0 17.0 39.0 29.0 17.0
TP 6 3 6.5 23.0 76.0 1.0 4.0 2.0 1.0
TP 7 4 8 25.0 74.7 0.3 4.0 1.0 0.3
TP 8 4 5.5 28.0 71.7 0.3 3.0 1.0 0.3
TP 9 3 6 20.0 78.4 1.6 7.0 3.0 1.6
TP 10 3 4 42.0 57.1 0.9 3.0 1.0 0.9
AVERAGES = 5.8 27.7 69.6 2.7 10.3 4.7 2.7
Other mitigating factors with regard to slope stability include:
• Mining slopes could be forced to fail and would not go flatter than a 1.4 (horizontal) to one (vertical)
due to the internal friction strength of the aggregate material (36 degrees). So, even if this material
failed to its "angle of repose" at 1.4:1, the failure surface would still be 30 feet within the property
limits.
• Although alluvium is conservatively modeled without cohesion, negative pore pressures and
cementing properties of natural minerals as groundwater dissipates can create near vertical mining
walls. Typically, the natural angle of repose is not achieved until the alluvium has been
mechanically sieved and stockpiled.
• CDOT could file a complaint at any point during the mining if erosion or mining slopes encroach or
endanger the Highway 85 structure and the DMG would require corrective action.
We believe that the proposed mining surface will provide a very high level of protection of the Highway 85
structure above and beyond what is required based on technical analyses.
Please call if you have further questions or concerns about the Lupton Lakes Project.
Sincerely,
Civil Resources, LLC /9
i~~i9'~s~~f i'~~.
Brad L. Hagen, P.E.
Civil Engineer l Principal
Z:brojetslSW Investment Group -1231SW TKO Joint VenWmIDMG PERMITVMequacy Rxviev.106jector letlers\CDOTCDGT-finalsbpestabil-050308.doc