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occurs. In this area, the southern flank of the model, there is no unit 2 or 3 <br />underlying the sandy silt. The unit lies directly on low permeability bedrock of the <br />Laramie-Fox Hills formation (see Sheet-1 ). The Boulder-Weld County Canal <br />(BWCC) runs through the upper layer approximately 300 to 500 ft south of the <br />south edge of the proposed pit at an elevation of approximately 4970 ft. <br />At one time, water leaking from the BWCC would daylight in groundwater seeps <br />down the hill slope just north of the ditch (see Sheet 1). A 6" drain was <br />constructed parallel to the ditch about fifty feet down-slope. It appears that the <br />drain is effective and that water from the BWCC seeps do not reach the <br />proposed gravel pit in the upper layer because the upper soils were not saturated <br />at the time of observation well drilling (July). The drain conducts the seepage <br />water to a location outside the gravel pit model area. <br />Water in this layer is unconfined (surface at atmospheric pressure) <br />1.3.2. Middle Clay Apuitard <br />The middle unit is composed of very low permeability clay (CL). It acts as a <br />confining layer on top of the lower gravel unit. It varies in thickness from 3 to 15 <br />feet thick. <br />1.3.3. Lower Gravel Aquifer <br />The lower unit is composed of gravel (GW) and ranges from 2 to15. feet thick in <br />the area. Local groundwater flows from the south through the gravel and <br />discharges to Boulder Creek. The groundwater in the gravel is under confined <br />conditions and has a peizometric or pressure head of about 2-3 feet above the <br />top of the unit. <br />File Pit 112 <br />Groundwater Modeling Report <br />2of6 <br />