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2.2.1. Upper Silt and Loess Laver <br />The upper silt and loess layer includes areas of clay (CL). This layer is <br />approximately 4-6 ft thick in the area of the proposed pit and becomes thicker <br />rapidly to the north concurrently with the rise in elevation. The layer is 35-40 ft <br />thick in the area where the Greeley Loveland Canal occurs. The Greeley <br />Loveland Canal runs through the upper layer approximately 420 ft north of the <br />proposed pit at an elevation of approximately 4940. <br />Perched ground water, which includes water leaking from the ditch, daylights at <br />several groundwater seeps along the hill slope just north of the proposed pit (see <br />Sheet 1). The seeps occur at a low permeability clay strata horizon acting as an <br />aquitard. Water from the ditch seeps do not reach the proposed gravel pit in the <br />upper layer. We know this because the upper soils were not saturated at the time <br />of observation well drilling (July). Because this layer is of low permeability and is <br />separated from the lower gravel aquifer by an aquitard we did not include it as an <br />active layer in the model. It is only represented in the model as a confining layer <br />above the lower gravel aquifer. <br />2.2.2. Lower Gravel Aquifer <br />The lower unit is composed of sand and gravel and is the major water bearing <br />strata in the area. The gravel occurs at a thickness of approximately 12-15 ft in <br />the area. Local groundwater flows from the north and west through the gravel <br />and discharges to the Big Thompson River. The groundwater in the gravel is <br />confined north of the proposed gravel pit and unconfined in pit area and south to <br />the river. <br />2.3. Aquifer Characterization <br />The characterization describes the direction of groundwater movement in this <br />shallow alluvial aquifer in and around the area to be excavated and defines <br />transmissivity, and storage coefficient of the aquifer in the area of excavation. <br />The direction of flow of groundwater in the alluvial aquifer is shown in Sheets <br />1,2,4 and 6 of the modeling report. Groundwater moves perpendicular to the <br />contour lines, generally downstream and sub-parallel to the river in the base and <br />post reclamation stages. During dewatering of each pit ground water moves <br />locally towards the pit. <br />Gardels Pit <br />Revised Groundwater Modeling Report <br />2of9 <br />