2008-06-17_PERMIT FILE - C1981018A

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11 J~'n / u, .~ vQ f . ~. ^, • 1._ ~~ ya I 4. f ' `', '~~~ ~~ .` . ~ U ~ V ..~'_~(.. i. ~... OO ~`. v <10 w J - U' ~~~'~ 0 1, ~~~~ f ~` ;. 4 .o .l .~,., :, .., ~ ~ti ,: ,~ .'~.. .. ._ 1 ~/ ~' ` ) \ .~ r; , ~._.E ~r i ~.,` o ._ I ~ ~ ~~ .~ ri~c .,,~ r.i '~:~5 ..?i .. 1 ~ r.l~ ~ ' .. ,/ G~ ,.~ .~ 1~1 ~~h f, ~.` 1r ,ti.;~ ~. ~-."•'~„ ~t ~' . ~. ~; :~' • ~~„ ,~ L ~'` 1 ~ (I ~ r r,S ~' `i1~\ ?, ~ Recharge of the Upper Sandstone Facies is from seepage into the rather permeable overlying colluvium and alluvium. Flow follows the general surface drainage pattern moving toward Red Wash to the east and toward the White River to the south. Recharge of the Lower Sandstone Facies, considering the generally impermeable nature of the overlying siltstone, is primarily from the north where these strata outcrop near Highway 40. This outcropping occurs because of the presence of the Red Wash syncline. The tendency for the flow in all three facies to tum southward within one or two miles of the White River rather than continuing toward the axis of the syncline implies that the flow is likely discharging into the White River alluvium. Stereoscopic and aerial observations give some evidence that the White River is following a fracture of fault in the area adjacent to the lease area which may be conveying the deeper groundwater up into the silty alluvium. Red Wash also may be following a fracture zone extending down Red Wash and Spring Creek, which permits water to move more readily to the south once the fracture sandstone is reached. The water table is from 50 to 200 feet under the surface in most of the area, and hence, the only evidence of seeps is where shallow, silty layers impede downward flow from an adjacent drainage. Vegetation along the White River does not show evidence of near-surface, long-lasting seepage. It is expected that groundwater flows primarily from the middle and upper sandstone facies into the White River Alluvium. However, because of the low permeability of these bedrock formations, this flow is ~ expected to be very limited. A rough estimate of the groundwater flow within the mine boundary as it flows r towards the river was made by utilization of the equation O = KA(dh/dl). In this groundwater flow equation, O is the flow (gpd), K is the aquifer permeability (gpd/ft~), dh/dl is the hydraulic gradient (fUft), and A (estimated at 6,000,000 ftz) is the cross-sectional area of the saturated zone perpendicular to the hydraulic gradient through which the flow occurs (ft'). The permeability, K, was estimated from the results of the aquifer tests in the upper sandstone facies in wells 36-2 and 2-7 to be 0.01108 gpd/ftz. The hydraulic gradient was estimated from the groundwater potentiometric maps prepared from the well level data to be 0.02857. The resulting estimate from this data is for a flow of about 1900 gpd (1.3 gpm) through the sandstone towards the river. Of course this estimate is based on limited data and cannot be expected to be accurate, but it does indicate that the aquifer is extremely tight and groundwater flow towards the White River from the upper sandstone formation within the mine plan area is very low. The lower sandstone facies is located below the White River alluvium within the mine plan area. Groundwater flow within the Red Wash alluvium is also expected to be quite low. A rough estimate of this flow was obtained by the same method as outlined in the previous paragraph for the flow within the bedrocks. The hydraulic gradient within the alluvium is expected to be about equal to the slope of the channel (dh/dl = 0.005). The permeability (K) was assumed to be approximately the same as the highest permeability measured within the White River alluvium (24,970 gpd/ftZ at Qal-3 from Ford, Bacon, and Davis, 1981). An average cross sectional area was estimated by assuming an average alluvial valley width of 500 feet and east and west sideslopes of approximately 20 and 10 percent respectively. Assuming that Permit Renewal #3 (Rev. 8/99) II.C-64