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Appendix B - Packer Test Methods and Results 6 <br />procedure in the next interval. If testing an existing borehole, pull the pack assembly out 50-75 feet and <br />set the packers in the next test interval. Repeat the test procedure . <br />11. After the completion of all packer testing, raise the packer assembly from the borehole, dismantle the <br />equipment, and transport it to the next borehole. <br />4. THEORY AND ANALYSIS <br />4.1 Theory - Darcy's Law <br />Permeability testing is at the heart of groundwater hydrology. It has its origins in Darcy's Law: <br />Q=KIA <br />where: Q = flow rate [L3T-'] <br />K = hydraulic conductivity [LT'] <br />I = hydraulic gradient [LL"'] <br />A = area [Q <br />This equation will provide an estimate the flow that will pass through a geologic medium if the head gradient <br />(1) causing the flow, the area (A) through which water is flowing, and the hydraulic conductivity (K) of the <br />medium are known. <br />. Hydraulic conductivity can be determined if Q, I, and A are known. The equation defines the hydraulic <br />conductivity as the constant of proportionality which relates flow to head, after adjusting for hydraulic <br />conditions (such as area and head gradient). Hydraulic conductivity is a characteristic of both the fluid the <br />medium through which the fluid is passing. <br />Expanding the gradient portion of this law: <br />Q = K)A <br />where: Q = flow rate [L3T"I] <br />K = hydraulic conductivity [LT'] <br />DH = hydraulic head change [L] <br />L = length of flow path [L] <br />A = area of flow path [Lz] <br />After re-organizing, the equation for the hydraulic conductivity is: <br />K AHQL ( Q A AHJ\ AJ <br />where: Q = flow rate [L3T'] <br />K = hydraulic conductivity [LT'l] <br />DH = hydraulic head change [L] <br />L = length of flow path [L] <br />A = area of flow path [L2] <br />This equation makes it clear that, in order to determine the hydraulic conductivity of a material, it is necessary <br />to set up the material of interest in a known geometric situation (L, A), and then pass a fluid through the <br />4109B.071116 Whetstone Associates 6