Determination of Aquifer Parameters at a Ground‐Water Recharge Site

Abstract

ABSTRACTPorous asphalt pavement is a storm‐water management technique which reduces runoff and enhances ground‐water recharge. Planned applications of this, or other ground‐water recharge techniques, require that ground‐water response to induced recharge be quantified. Here, we emphasize determination of the aquifer parameters hydraulic conductivity (K) and specific yield (Sy) at a porous asphalt ground‐water recharge facility installed near Willow Grove, Pennsylvania.We compare values of these aquifer properties derived from conventional laboratory and field techniques to those derived using recharge event data collected at the site. By the comparisons, we illustrate the techniques of aquifer property determination apropos to the design of ground‐water recharge installations. Because of the fractured nature of the aquifer, the K‐values determined from pumping test and slug test analyses are about an order of magnitude greater than those of rock core samples, while the field‐based specific yield values are about an order of magnitude less than effective porosities of the rock cores. Ratios of K/Sy derived from a chemical tracer test agree with the pumping test values. Finally, the K and Sy necessary to simulate facility response to recharge using a numerical model of ground‐water flow correspond to those derived from field‐oriented techniques rather than those of the rock cores.The results show that the design parameters K and Sy should be obtained from field‐based techniques, such as the nonsteady pump test, which match the time and space scale in which the facility is expected to affect the aquifer.