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34 Grassy Valley hydrologic conditions <br />Table 4.4 Areas used in water balance <br /> Current Mining and <br />Area Conditions Post-mining <br /> ft2 ft~ <br />Total GV drainage above GV-3 55,586,560 55,586,560 <br />Riparian Area (planar) 2,284,595 2,284,595 <br />Planar undisturbed diatreme area 29,771,232 18,727,200 <br />Sloped undisturbed diatreme area 30,358,662 19,028,169 <br />Planar undisturbed granite area 25,815,328 22,573,892 <br />Sloped undisturbed granite area 26,230,212 22,936,682 <br />• Planar area of ECOSA NA 7,897,523 <br />Area upgradient of ECOSA draining to GV-02 NA 2 306,247 <br />Area upgradient of ECOSA draining to WHEX NA 665,813 <br />WHEX area in Grassy Valley NA 6,387,927 <br />Planar areas were used to calculate all volumetric parameters in the water balance except <br />ET, which was calculated on the basis of sloped areas. This was considered to be more <br />representative of the surface from which ET actually occurs. <br />Flow rate measurements at GV-03 <br />Measured flow rates at GV-03 were obtained from CC&V. Table 4.1 presents available flow <br />rate data and also the average monthly values used in the modeling. In some cases there <br />were no data for a particular month, in which case an estimate of the expected flow rate was <br />made. <br />4.4.5 Calculations <br />This section documents the way calculations were performed in the GoldSim model for the <br />current, mining, and post-mining conditions. <br />Water contributing to segments: <br />Water volumes contributing to individual segments during each timestep were calculated in <br />the following way: <br />(Snowmelt + rainfall) x segment area <br />This calculation was performed separately for riparian areas, areas underlain by diatreme, <br />and areas underlain by granite. In the mining and post-mining scenarios, water volumes <br />were also calculated for the area overlain by the ECOSA, areas upgradient of the ECOSA <br />and the WHEX area. <br />Evaporation and ET from segments: <br />Evaporation from riparian areas was calculated as: <br />Drainage area x pan evaporation rate x factor to convert to evaporation from riparian <br />areas <br />2736 <br />Cripple Creek 8 Victor Gold Mining Company <br />Water Management Consultants <br />