1981-11-13_PERMIT FILE - C1981013 ‎(47)‎

• Permit No: C1981013
• IBM Index Class Name: PERMIT FILE
• Doc Date: 11/13/1981
• Doc Name: Geotechnical Investigation
• Section_Exhibit Name: Volume 2 Exhibit 15
• Media Type: D
• Archive: No

Water, Waste & Land, Inc.
CONSULTING ENGINEERS &SCIENTISTS
­7
January 20, 1982
Mi GNU �E'3ARTMENT
CF&I Steel Corporation Re: Stability Analysis
P.O. Box 316 Mine Waste Piles
Pueblo, CO 81002 Allen and Maxwell Mines
WWL #8105
Attn: Mining Department
Mr. Jack D. Gillespie
Gentlemen:
In response to your purchase order No. M12180, dated 12/04/81 , we have
conducted a study on the proposed coal mine waste piles at your Allen
and Maxwell Mines near Weston, Colorado. This work has included laboratory
identification and shear strength testing of waste material , and a
stability analysis of the piles to evaluate their anticipated behavior.
The purpose of this report is to summarize the laboratory testing data
and present the results from the stability studies.
Laboratory Testing
Laboratory identification and shear strength tests were performed on a
sample of coal mine spoils as provided by CF&I. As we understand it,
this sample was obtained from the existing piles at the Allen Mine. The
result of the identification testing is shown on Figure 1 . Included in
this testing was specific gravity of the solids, grain size distribution
of the granular portion and Atterberg Limits of the fines. By the Unified
system, the spoil classifies as an SW-SC soil which is a well graded sand
to clayey sand with some organics. The spoil is considered to be "soil-
like granular" by OSM "Guidance Document for the Disposal of Excess Spoil"
(in press) . The results of a moisture-density test conducted on the
portion of spoil finer than the No. 4 sieve is presented on Figure 2.
The maximum dry density of the minus 4 material is about 93.2 pounds per
cubic foot at an optimum water content of 12.9%. When corrected for the
percent of coarse material , the maximum dry and wet density of the entire
sample is about 98. 3 and 108. 1 pounds per cubic foot.
The results of direct shear testing is presented on Figure 3. This test
was conducted according to ASTM D-3080, Standard Method for Direct Shear
Test of Soils Under Consolidated Drained Conditions" using minus No. 4
sieve size materials. The results indicate that the spoil is cohesionless
1311 South College Avenue, Fort Collins, Colorado 80524 [phone]