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0 <br />4.4.1.21NFILTRATION <br />Figure 3 depicts the calculated net flux through the layers of the modeled <br />prescriptive final cover profile for the constant potential bottom boundary <br />condition. As shown therein, infiltration potential for the prescriptive final cover <br />is estimated to be about -0.69 inches/year. This value represents the performance <br />for a degraded clay prescriptive final cover over the FSL. <br />4.4.2 ALTERNATIVE FINAL COVE <br />As summarized above, the FSL non -prescriptive cover was modeled as a four foot <br />thick (1219 -mm) alternative cover composed of compacted on-site borrow soils <br />combined with shallow to intermediate rooting native vegetation. The results of <br />the modeling performed for this study are presented in Figures 4 and 5. <br />4.4.2.1 SOIL MOISTURE RESULTS <br />Figure 4 depicts the modeled moisture content of the alternative final cover soils <br />in percent by weight for several distinct depth intervals over a period of <br />approximately ten years. Figure 4 represents the moisture conditions anticipated <br />under the constant potential bottom boundary and also summarizes the rainfall <br />history recorded at the Western Regional Climate Center's Stockton Station. As <br />can be seen, the soil layers mimic seasonal precipitation patterns throughout the <br />modeling period, though only the larger events penetrate to the deeper soil layers. <br />4.4.2.2 INFILTRATION <br />Figure 5 depicts the net flux through the layers of the modeled alternative final <br />cover profile under a constant potential bottom boundary condition. As shown, a <br />negative flux potential of about —12.60 inches/year is calculated. <br />Figure 5b presents the net flux as a function of depth through the modeled profile <br />for several different cover thicknesses and clearly illustrate the negative flux <br />potential increasing (i.e., total system performance improving) as the cover <br />section thins. <br />t 1 _ . �1iT.Y.y ��7►1 <br />5.1 INFILTRATION <br />As clearly shown in Figure 4, a substantial drying of final cover soils constructed <br />at the FSL is expected. As indicated on Figure 5, this drying is expected to result <br />in cumulative negative flux of as much as —12.60 inches per year for the 4 -foot <br />cover section. <br />RM <br />C:\2003-033%EDOM HILL ALTERNATIVE COVER.DOC\6/16/2005 <br />Geologic Associates <br />