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a <br /> ' By applying the above boundary conditions, assuming ideal gas flow, and integrating to solve for <br /> the pressure p(r), Darcy's law becomes: <br /> P(r) = Cp.2 - q.TuP,, / (19 88khT.) ln(r,/r)]'fi (3) <br /> where. p(r) = pressure at a radius r, psi <br /> P, = pressure at outer boundary, psi <br /> q= = air extraction rate, cfd <br /> T = soil temperature, 515 OR <br />' Tx — temperature at which qx is measured, 520 OR <br /> A = air viscosity, 0.018 centipoise (cp) <br />' pw = pressure at which %. is measured, 14.7 psia <br /> k = air permeability, darty <br /> h = height of the extraction interval, ft. <br /> r. = radius of influence, ft. <br /> r = radius, ft. <br />' Equation (3) can be applied to the steady-state pressure responses observed in the field to <br /> calculate the soil transmissibility and radius of influence <br />' Estimates of transrrussivlties and radii of influence have been calculated for pairs of observation <br /> wells that meet the following criteria. <br /> 1. The distances of the two observation wells from the test wells should differ by a minimum <br /> of 10% <br /> 2. The difference in vacuum pressures between the two observation wells should be at least <br /> 0 3 in. H2O, and the two observation well pressures should be non-zero <br /> 1 These conditions allow better definition of the vacuum gradient in the computation of the air <br /> transmissibility and the radius of influence. <br /> 1 <br /> 1 <br /> 1 D-2 _ <br />