2018-07-10_PERMIT FILE - M2018037 (4)

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Mr. Mark Johnson May 31, 2018 Page 2 GEOTECHNICAL CONDITIONS Based on the site investigations, the natural site stratigraphy generally consists of three main units: 1) Overburden generally consisting of near surface sandy clay to silty sand; 2)sand and gravel alluvial deposits that underlie the overburden and overlie the bedrock; and 3) bedrock usually consisting of sandy claystone, siltstone, and sandstone that is commonly weathered in the top foot and is commonly interbedded. Overburden The overburden typically grades from a sandy clay to a silty sand that is of low plasticity typically ranging from approximately 2 to 5 feet in thickness. This unit is usually slightly moist to moist and stiff to very stiff or medium dense with the top 6 to 8 inches containing significant organics. Sand& Gravel The sand and gravel encountered is present throughout the site typically underlying the overburden and overlying the bedrock and ranges from approximately 20 to 43 feet in thickness. This unit typically consists of slightly silty,fine to medium grained, locally coarse grained sand with local sandy gravel also present. Local thin sandy clay to clayey sand lenses were locally encountered within this unit. Where encountered, gravels were typically 1 to 2 inches in diameter. Local cobbles up to 4-inches were also locally encountered. Bedrock The bedrock was encountered at depths ranging from approximately 23 to 46 feet below the ground surface in the exploratory borings. Bedrock was generally weathered in the upper one foot typically became harder in unweathered zones. The bedrock consisted of claystone, siltstone and sandstone that were commonly interbedded. Local lignite was also encountered. The claystones are typically moderately to highly plastic. The siltstones and sandstones are non- plastic to lowly plastic. Groundwater Groundwater was encountered in all of the borings at approximately 4 to 14 feet below ground surface. The groundwater levels will vary seasonally and will typically rise during the irrigation season and during high river stages. Groundwater will be controlled with the proposed below grade slurry walls and by pumping down the water level during mining. After slurry wall construction, groundwater mounding is anticipated on the upgradient(south and west) side of the site and a groundwater shadow(deeper water table) is anticipated on the downgradient(north and east) side the site. From a geotechnical standpoint, the sand and gravel will form the majority of the mine slopes. These soils are generally strong and stable, particularly when dewatered. STRUCTURES WITHIN 200 FEET OF DISTURBED AREAS The known, permanent, man-made structures within 200 feet of the proposed mine areas that are not owned by Bestway Concrete (aka Tricycle Lane Texas, LLC) are listed below: • Weld County Road 14.5 and ROW( North Boundary, Weld County Public Works) • Overhead Power Line (North Boundary at Weld County Road 14.5, United Power) • Overhead Power Line (West Boundary, United Power) • Overhead Power Line (South Boundary) • Water Line(North Boundary, Central Weld County Water District) • Various Gas Lines (Kerr-McGee/Anadarko & KP Kaufman) • Various Gas Well Infrastructure and Roads(Kerr-McGee/Anadarko &KP Kaufman) • Inouye 44-36 Well Head (Between SW and NW Cells, KP Kaufmann) • Funakoshi Sam Gu NO2 (East of NE Cell, Kerr-McGee/Anadarko) • Inouye 9-36A Well Head (NE Cell, Kerr-McGee/Anadarko)