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ti <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) W [p.2 - q.Tµp. / (19 88khTj ln(rJr))'/2 (3) <br /> where p(r) = pressure at a radius r, psi <br /> P. = pressure at outer boundary, psi <br /> qx = air extraction rate, cfd <br /> T — soil temperature, 515 OR <br /> T,, = temperature at which qc is measured, 520 OR <br /> µ = air viscosity, 0.018 centipoise (cp) <br /> p& = pressure at which qx is measured, 14 7 psis <br /> k = air permeability, darcy <br /> h = height of the extraction interval, ft. <br /> rG = 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 trans missivities and radii of influence have been calculated for pairs of observation <br /> wells that meet the following cnteria- <br /> i1 The distances of the two observation weIIs 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 /> These conditions allow better definition of the vacuum gradient in the computation of the air <br /> transmissibility and the radius of influence. <br /> J <br /> D-2 <br />