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16-21 is expected, owing largely to complex geologic at{ucture laee Figure 1, Tab 6, • Geology) which governs flow Sn the Trout Creek Sandstone and the proximity and occurrence of its outcrop to the south. In a~idltlon, operation of SCC'e Seneca II-W production well (Figure 8a, Attachment 16-2, Tab lE•) will influence the pattern of drawdown from the Yoast well into a non-concentric pattern. For drawdowns greater than 50 feet In the immediate vicinity of the Yoast ve~l 1, the clrawdovns will mimic a concentric shape; however, for dcawdowns beyond the 50--foot value, effects from geologic structure and proximity of boundaries become more pronounced, hence the non-concentric diawdown pattern. The significance of tha Yoast production well pumpage on hydraulically connected streamflovs and the local Trout Cceek aquifer 1s not only dependent on the magnitude, extent, and duration of the impact, but the local water uses of the streams and the Trout Creek aquifer. Three wells associated with the Foidel Mine to the southeast of the Yoast Mine, in addition to SCC':a Seneca II-W production well, produce water from the Trout Creek Sandstone. The Foidel Creek Mine wells are proximate to the one-foot drawdown radius predicted for operating both the Seneca II-W and Yoast production wells Sn Che year 2004 Isee Figure Ra, Attachment 16-2, Tab 161. Assumptions used Sn the model included constant pumpage of 35 gallons per minute at both wells. Constant pumpage at the Seneca II-W production yell was assumed for 15 years and at the Yoast production well for 9 years. These pumpage scenarios used to predict the maximum one-foot drawdown radius for both yells at year 2004 were overestimated (see Page 2, Attachment 16-2, Tab 16). pumpage records documented from 1991 through 1994 for the Seneca II-W production well as a requirement of the Seneca. II-W Mine Water Rights Augmentation Plan shoe average annual pumpage rates range from 1.70 up [0 10.6 gallons per minute. The highest rate (10.6 gpm) occurred in 1992 and vas approximately 30 percent of the assumed constant pumpage rate used in the model to predict dravdovn radii. pumpage decreased during the non-irrigation season ac the Seneca II-W Hine when operational requirements were low. SCC expects similar operational requirements at the Yoast Mine, and Yoaet production well pumpage races co also be significantly lover than 35 gpm for the duration of the Yoast life-of- mine. Significantly lover pumpage rates at both production wells will result Sn shorter one-foot dravdovn radii, including the radial distance towards the southeast and Che Foidel Creek Mine yells. SCC expects the lover, realistic pumpage rates anticipated for both yells for the life-of-mining will reduce the model-predicted radial distance of one- foot dravdovns towards the southeast, rendering any potential impact to the three Foidel • Creek Mlne wells completed in the 'f rout Creek Sandstone unmeasurable and Insignificant. Since SCC owns and operates the Seneca II-W production yell, any impacts to this yell from 14 Revised 11/01/95