Laserfiche WebLink
• • • <br />Project: Cripple Creek Geohydrology Date: 418/2008 <br />Task: Summary Page 1-2 <br />MODEL <br />A model of the hydrology of the Cripple Creek Mining District has been constructed, and is presented in "Model". <br />The model uses the following concepts to create a working analog of the hydrology system: <br />1. Water enters the modeled area by infiltration at some rate from the surface <br />a. Without interception in unaffected areas and mined areas <br />b. With partial interception in areas of overburden storage (mines, storage areas) <br />2. Water flows to the Carlton Tunnel: <br />a. Water drains rapidly (and at a variable rate) from the diatremal area directly penetrated by the tunnel <br />b. Water drains slowly (and at a constant rate) from the rest of the Diatreme and the granite <br />3. Flow exits from diatreme by a resistive flow conduit to Carlton Tunnel <br />4. Water is stored in the diatreme by build-up of water level <br />The model is set up using the observed monthly precipitation for the period 1992-2007. <br />The model is calibrated using the (corrected) flow from the Carlton Tunnel, with the best fit following flow average and variations. <br />The results of the model are as follows: <br />1. Pre-mining infiltration to the deep groundwater system (in the diatreme and the granite) is -25% (5 inches per year). <br />2. Infiltration to the south lobe of the diatreme affects the short-term flow from the tunnel, causing the observed flow variations. <br />3. Infiltration to the rest of the diatreme and the granite within 2000 feet of the rim, provides the (constant) base flow at the tunnel. <br />Calibration shows that infiltration from disturbed mining areas has reduced during mining, due to interception by overburden and the VLF. <br />The reduction in infiltration in this area has had a minor and temporary impact on flows, reducing the infiltration approximately 12% recently. <br />When the overburden materials reach their field capacity (-7.5% moisture content by volume) the flow will return to pre-mining rates. <br />This is expected to require approximately 10-50 years after the placement of the overburden materials in storage areas or mines as backfill. <br />Adrian Brown Consultants, Inc.