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Month <br />Potential <br />ET (in.) <br />Precipitation <br />(in.) <br />Actual <br />ET (in.) <br />Runoff <br />(in.) <br />Infiltration <br />(in.) <br />Percolation <br />(in.) <br />October <br />3.36 <br />2.36 <br />2.12 <br />0.24 <br />2.12 <br />0.00 <br />November <br />2.19 <br />2.16 <br />1.94 <br />0.22 <br />1.94 <br />0.00 <br />December <br />0.48 <br />1.80 <br />0.48 <br />0.18 <br />1.62 <br />0.00 <br />January <br />0.47 <br />1.09 <br />0.47 <br />0.11 <br />0.98 <br />0.00 <br />February <br />1.94 <br />0.48 <br />1.94 <br />0.05 <br />0.43 <br />0.00 <br />March <br />2.93 <br />0.17 <br />0.30 <br />0.02 <br />0.15 <br />0.00 <br />April <br />3.70 <br />2.41 <br />2.17 <br />0.24 <br />2.17 <br />0.00 <br />May <br />4.93 <br />1.78 <br />1.60 <br />0.18 <br />1.60 <br />0.00 <br />June <br />5.72 <br />0.62 <br />0.56 <br />0.06 <br />0.56 <br />0.00 <br />July <br />6.34 <br />1.20 <br />1.08 <br />0.12 <br />1.08 <br />0.00 <br />August <br />5.74 <br />1.10 <br />0.99 <br />0.11 <br />0.99 <br />0.00 <br />September <br />4.43 <br />4.70 <br />4.23 <br />0.47 <br />4.23 <br />0.00 <br />Annual Total <br />42.23 <br />19.87 <br />17.88 <br />1.99 <br />17.88 <br />0.00 <br />• the pile by ET in later months. Monthly estimated ET exceeds monthly precipitation <br />during all months of the year. <br />• <br />• <br />Section 13 <br />Geochemical Data and Analysis <br />Exhibit 13 -2 presents a similar estimate using precipitation conditions the occurred <br />during the wettest year on record, 1997. <br />Exhibit 13 - 2. Estimated percolation through development rock areas or wettest year on record. <br />The estimate summarized in Exhibit 13 -2 for the wettest year on record indicates that <br />potential ET exceeds precipitation by a ratio of approximately 2.1:1, and suggests that <br />water infiltrating the pile also evaporates during the year. During the months of <br />December and January, the monthly precipitation exceeds the estimated monthly ET. <br />Therefore, stored moisture within the rock pile would be expected to increase during <br />December and January. However, excess ET occurring in latter months is estimated to <br />be adequate to remove this moisture through evapotranspiration, preventing <br />percolation through the pile. The primary ET mechanism contributing to this water <br />balance assessment is evaporation. <br />Unsaturated Flow Modeling: Unsaturated flow modeling was used to estimate <br />percolation through the rock piles in a more rigorous manner. UNSAT-H (Fayer 2000) <br />is a Fortran -based model that is used to simulate the one - dimensional flow of water, <br />vapor, and heat in soils. The code addresses the processes of precipitation, <br />evaporation, plant transpiration, storage, and deep drainage. The procedure for this <br />estimation included: <br />• Estimate physical and hydrological characteristics of development rock using site <br />specific sampling and laboratory analyses. <br />• Compile climate data from locations as close as possible to the site. <br />• Estimate percolation through development rock areas using UNSAT -H. <br />C: \Documents an{I Settings\ cwoodward .DMC \DesktarAEnvironmental Protection Plan Sunday Mines Revised November 2011 rev1 12) 11 10 11.docx <br />13 -7 <br />