2024-06-04_REVISION - M1987113 - Laserfiche WebLink

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Mr. Chris Oestreich June 29,2023 Page 2 The borings were logged by a representative of Civil Resources. During drilling the cuttings were observed to get an indication of the rock and matrix percentages. In addition,the subsurface samples were logged in the field.Logs and notes regarding the drilling operations are induded on Figure 2. Subsurface Conditions Based on the borings drilled,there appear to be three geologic units at the site. These units are herein referred to as 1) the Aggregate Unit,2)a Finer Grained Alluvial Unit that locally underlies the Aggregate Unit and overlies the bedrock, and 3)Bedrock Unit. These units are described as follows: 1) Aggregate Unit–This unit lies at the surface east of the"hogback"and is described as dense to very dense;boulders,cobbles,and gravel in a clayey sand matrix. This unit is typically moist becoming wet below the groundwater table. When washed and processed,the aggregate is grey. The clayey sand matrix is typically red. Local clayey sand lenses are present within this unit. The estimated rock to matrix ratio ranges from 20 percent rockl80 percent matrix to 100 percent rock/0 percent matrix. The average estimated rock to matrix ratio is 71 percent rock and 29 percent matrix. This unit ranged from approximately 21 to 101 feet in thickness. The thickness will tend to be less near the"hogback". We interpret this unit as the mineable unit. 2) Finer Grained Alluvial Unit—This unit locally underlies the Aggregate Unit and was encountered in boring TH-1 at the base of the mine and in TH-3 in the north part of the mine. This unit is described as a dense to very dense;clayey to very clayey sand with occasional cobbles and gravel. This unit is very moist. The thickness of this unit ranged from greater than 15 feet to approximately 28 feet where encountered. Due to the relatively low occurrence of gravel and cobbles,we consider this to be an unmineable unit. 3) Bedrock Unit–This unit is daystone of the Laramie Formation. This unit underlies the Aggregate Unit and the local Finer Grained Alluvial Unit. In borings TH-2,TH-4,and TH-5;the claystone lies directly below the Aggregate Unit. The claystone is typically hard,moderately to highly plastic,moist,and grey. In borings TH-3,TH-4,and TH-5:groundwater was present at depths ranging from approximately 57 to 65 feet below the premining surface. In boring TH-1,drilled near the current mine bottom,groundwater was encountered at a depth of approximately 39 feet. The shallowest boring(TH-2, near the"hogback")did not encounter groundwater at the time of drilling. Laboratory Data Civil Resources tested the clayey sand material that remains after processing the aggregate. Two samples were analyzed for gradation,Atterberg Limits,Standard Proctor moisture/density relationships,and remolded permeabilities. The laboratory results are attached. The results indicate that the soil classifies as a clayey sand with a remolded permeability on the order 10 E-7 centimeters per second. In addition,laboratory testing(gradation and Atterberg Limits)was performed on two soil samples obtained from shallow test pits excavated in the area of the relocated ditch. These lab tests are also attached. STRUCTURES WITH 200 FEET OF DISTURBED AREAS The known,permanent,man-made structures within 200 feet of the proposed mine limits that are not owned by the miner are listed below. 1. Westgate Road located approximately 55-feet south of the mine at its nearest point. 2. A small building located on the south side of Westgate Road approximately 80 feet from the mine. 3. A railway line located approximately 185 feet from the mine at its dosest point near the southeast corner of the mine.