2008-03-25_PERMIT FILE - M2008017 (2)

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A A 1 1 1 1 1 1 1 1 1 1 Preliminary Sand~and Gravel Mineral Evaluation 29 Acre Parcel -East of Balsam Avenue Greeley, Weld County, Colorado Project No. 20015242 Terracon The stratification boundaries shown on the encosed boring logs represent the approximate locations of changes in soil types; in-situ, the transition of materials may be gradual. According to the Soil Survey of Weld County, Colorado and as shown on the enclosed soil conservation map, Figure 2 in Appendix A, the soils at the site consist of: 3 - Aquolls and Aquents, gravelly substratum ~ -.~ • 10 - Bankard sandy loam, 0 to 3 percent slopes. /~- L, ~ ~ `~ 68 - Ustic Torriorhents, moderately steep. ~/~~ ~~ B-c i Field and Laboratory Test Results Field test results indicate that the overburden silty clayey sand layers are medium dense in relative density. The coarse sand with gravel stratum varies from loose to dense in relative density and the bedrock stratum varies from weathered to hard with depth. CONCLUSIONS AND DISCUSSION It is Terracon's understanding that the area under evaluation, approximately 29-net acres, based on plan line dimensions, is being considered as a potential gravel pit. Based on this preliminary investigation and number of test borings drilled at the site, it is Terracon's opinion the sand with gravel material encountered during the field exploration at various depths is suitable for use as construction aggregate material. The sand and gravel materials appear to satisfy the quality requirements to meet Colorado ~ Department of Transportation specifications for Class 1 Structure Backfill, Class 1 to 3 Aggregate Base Course and could be processed to obtain Class 6 and 7 Aggregate Base Course if the course aggregate meets durability requirements. The gravel encountered appears to be of good quality and contains durable rock fragments composed of igneous and m~famorphic rock fragments. The overburden thickness encountered in the test borings ranges from approximately 2-112 to 11-feet in thickness. The underlying granular sand with gravel strata thicknesses encountered during the drilling operations, (based on available information provided to Terracon for the Layne-Western borings) ranges from approximately 57 to 84-1/2-feet. Based on these thicknesses, plan line dimensions for the proposed 29-acre parcel, and approximate areas of potential mining operations, there are approximately 0.3 million cubic yards of overburden material that will have to be removed to obtain approximately 3.S million cubic yards of s na d and gravel material. Hence, the average ratio of sand and gravel volume to overburden 5 ~,.