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Mr. Norm Roche Match 7, 2001 Page 2 SITE GEOLOGY ~~ Inc In the mine area, bedrock units dip gently east-southeastward away from the Rocky Mountain Front Range into the Denver Basin. Regional geologic mapping (Colton, 1978) indicates the near surface bedrock at the mine is most likely claystone of the upper shale member of the Pierre Shale. The mapping indicates that at the mine, bedrock is overlain by two Fluvial alluvium units known as the Piney Creek and Post-Piney Creek Alluvium. Logs of forty-two exploratory borings drilled at the site by Aggregate Industries West Cenral Region, Inc. provide data on the site stratigraphy. The logs indicate that the general stratigraphy south of Saint Vrain Creek consists of none to approximately five feet of overburden overlying approximately four to nine feet of sand and gravel on top of bedrock. The boring data indicates the material overlying bedrock south of Saint Vrain Creek ranges from approximately eight to eleven feet in total thickness. Boring data north of Saint Vrain Creek indicates the general subsurface profile at the north part of the mine consists of none to approximately five feet of overburden overlying approximately seven to 19 feet of sand and grave! on top of bedrock. The boring data indicates the total thickness of material overlying bedrock at the part of the mine north of Saint Vrain Creek, ranges from approximately eight to 22 feet. Overburden soils are fine grained and commonly gravelly. Groundwater levels in the borings range from approximately four to ten feet below the ground surface. From a geotechnical standpoint, the sand and gravel will everywhere form most of the mine slope profiles. These soils are generally strong and stable particularly when dewatered. STRUCTURES WITHIN 200 FEET OF DISTURBED AREAS The Fredstrom mine is located in an agricultural area with relatively few man-made structures. Sttvctures within 200 feet of the mine limits include ponds, roads, houses, utilities and irrigation ditches. For this study we did not consider irrigation ditches because agreements between the mining and ditch companies will be reached prior to mining. All known man-made structures, exclusive of irrigation ditches, and their approximate closest distances from the mine area limits and the mine highwalls are outlined below. Structure Approximate Distance From Mine Limits (ft) Approximate Distance From Mine Highwall (ft) St. Vrain Road and utilities 30 170 Waterline in and near St. Vrain Road 20 130 Overhead power line on St. Vrain Road 60 210 Shed south of southeast corner of mine 60 85 Sheron Golden House on St. Vrain Road 1 ~0 520 Suzanne Ball House on St. Vrain Road 60 250