Laserfiche WebLink
- Probable HydrolaRit Consequences - Chimnty Rock Mine <br />T = Kb or K =T/b <br />a <br />+: Given: <br />1 <br />T = 210 g/d/ft or 28.07 ft~/day (7.48 g/ft') <br />b=50ft <br />K = 28.07ft2/day/SOft <br />K = 0.5614 ft/day <br />Considering the possible effects of infiltration from the pit areas, a velocity calculation can be <br />performed based upon the parameters determined for the Fruitland Formation in the report by <br />Piteau and Associates (1982). Seepage velocity (v,), the true velocity representing the rate the <br />groundwater flows through the pore spaces can be calculated utilizing the formula: <br />v, = Kdh/rredl <br />where K is the hydraulic conductivity, dh is the vertical difference in ground water elevation <br />between two points, n< is the effective porosity, and dl is the distance between the two points <br />(Fetter, 1981). Assuming an effective porosity of 0.15, and determining the hydraulic <br />conductivity from the transmissiviry data of 1982 (approximately 210 g/day/ft), the distance and <br />height (gradient) of 0.25 fUft (Piteau and Associates, 1982) then: <br />v, _ (0.5614 ft/day) (50 ft) / (0.15) (200 ft) <br />v, = 0.94 ft/day <br />This indicates that the velocity of ground water movement through the Fruitland Formation is <br />adequate for infiltration to have taken place since the time of pit backfilling. The pit in this area <br />was backfilled in 1985; therefore, degradation to the water quality or quantity in the area would <br />have apparently occurred prior to the present. <br />Since the alluvial aquifer and the stream are hydraulically connected, the effects observed in the <br />aquifer should be apparent in the stream. The effects that have been observed in the alluvium and <br />the stream would be represented by the data from the up and downgradient monitor points. Data <br />from surface monitoring stations and wells is presented in Appendix I. <br />Data from the wells W-7 (located upgradient) and W-5 (located downgradient) from the September <br />1989 sampling event were compared to determine impacts to the shallow alluvial aquifer. The <br />comparison of these two results indicates the water quality actually improves in the downgradient <br />well. This data indicates that the alluvial aquifer has exhibited relatively little impact, if any. <br />Revised hydrologic-053\OS-22-0(1:26PM) 9 <br />