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where: R = Effective radial distance over which the head <br /> difference is dissipated, <br /> rk, = Radial distance between well center and <br /> undisturbed aquifer, <br /> L = Height of perforated section of well through <br /> -- which ground water enters <br /> Yo = difference in head elevation at time zero, <br /> Yt = difference in head elevation at time t, and <br /> t = time since Yo. <br /> When the observed water elevation data are plotted against <br /> time (t) on a semi-logarithmic paper (t on the arithmetic <br /> scale) , the data points should produce a straight line. <br /> The data begins to deviate from the straight--line <br /> relationship at a small change in water table head. The <br /> straight-line portion of the curve should be used to <br /> evaluate 1/t•ln(YO/Yt) and calculate R. The results of <br /> this method are generally considered appropriate as a means <br /> of estimating the hydraulic conductivity within an order of <br /> magnitude (Thompson, 1987) . <br /> 4.2 Field Procedures <br /> Prior to the aquifer test, depth to water was first measured <br /> in all eight monitoring wells located on- and offsite. Since <br /> a permit to discharge the pumped ground water into the city <br /> sewer.- was denied, Armour Petroleum, a certified hazardous <br /> -- waste hauler, was contracted to remove and dispose of the <br /> aquifer test ground water. <br /> An aquifer pump test was first attempted at the site to <br /> evaluate aquifer characteristics. The pumped well was MW-3, <br /> while the drawdown effects were measured in MW-4. The pump <br /> test, however, had to be terminated because the tank in the <br /> truck filled up immediately before sufficient data could be <br /> obtained. <br /> t <br /> -- After the water levels stabilized following the initial pump <br /> test, a slug test was then performed on MW-3 and MW-4 by <br /> introducing clean water and recording the subsequent drop in <br /> water level over time. The slug test was terminated when the <br /> depth to water readings reached the original depth to water <br /> reading before the test started. <br /> 4.3 Analysis of Aaui ,gr Parameters <br /> A computer program was used to statistically analyze the test <br /> data using regression analysis and to calculate the hydraulic <br /> conductivity of the aquifer. <br /> 11 <br />