1994-01-01_PERMIT FILE - C1981017 (5)

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February 8, 1994 Mid - Continent Resources P.O. Box 1298 Glenwood Springs, Colorado 81602 Attention: Diane Delaney Subject: Laboratory Testing Mid - Continent Road Materials Redstone, Colorado Job No. 21,006 1971 WEST 12TH AVENUE • DENVER. COLORADO 80204 • (303) 825 -0777 CTL /THOMPSON, INC. CONSULTING GEOTECHNICAL AND MATERIALS ENGINEERS This letter transmits the results of laboratory testing we performed on four samples of road 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 5. A relative density test was performed on the material from #4 Road to determine the maximum dry density. 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