_GENERAL DOCUMENTS - C1981017 ‎(226)‎

• Permit No: C1981017
• IBM Index Class Name: GENERAL DOCUMENTS
• Doc Name: Bid Documents ‎(IMP)‎
• Permit Index Doc Type: General Correspondence
• Media Type: D
• Archive: No

CTL/THOMPSON, INC.
CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS
February 8, 1994
Mid-Continent Resources
P.O. Box 1298
Glenwood Springs, Colorado 81602
Attention: Diane Delaney
Subject: Laboratory Testing
Mid-Continent Mine Materials
Redstone, Colorado
Job No. 21,006
This letter transmits the results of laboratory testing we performed on four samples
of mine material submitted to our laboratory November 17 ,1993. The samples were
tested in accordance with applicable American Society for Testing Materials (ASTM)
standards. Tests performed include material gradation, Atterberg limits, modified Proctor
compaction, slake durability, and direct shear.
The bucket samples supplied to us were measured for natural moisture and
density. The approximate volume and measured weight of material in each bucket were
used to determine the density of the loose sample in the bucket, while a small sample
was oven dried to determine the moisture content. A gradation analysis was performed
for each material to aid in classification (Figs. 1 and 2). A sample of minus 3/4 inch
material was screened from each sample to perform a modified Proctor compaction test
(ASTM D 1557). The curves were used to determine the maximum dry densities and
optimum moisture contents, as illustrated in Figs. 3 through 6. Atterberg limits (ASTM D-
4318) were measured for sampled materials passing the #40 sieve. Laboratory results
are summarized in Table I.
The Slake Durability Index was measured for each material according to ASTM D-
4644. The specimen for each test consisted of ten representative, intact, roughly
equidimensional fragments weighing 40 g to 60 g each. The fragments were selected
from the bucket samples. The Slake Durability Index reported in Table I is the percentage
by dry mass retained on a No. 10 Sieve after two cycles of oven drying and 10 minutes
of soaking in water with a standard tumbling and abrasion action.
The direct shear tests (ASTM D 3080) were performed on minus 3/8 inch material.
The samples were compacted to approximately 90 percent of maximum dry density at
optimum moisture content, as determined in the modified Proctor compaction test.
Additional water was not added to the specimen during the test and the materials were
allowed to drain. The tests were performed by deforming a specimen at a controlled
strain rate on a single shear plane. Three specimens were tested for each material, each
under a different normal load, to determine the effects upon shear resistance and
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