Accounting for Anomalous Hydraulic Responses During Constant-Rate Pumping Tests in the Prairie Du Chien-Jordan Aquifer System – Towards a More Accurate Assessment of Leakage

The Prairie du Chien-Jordan Aquifer system is an important source of drinking water for residents of southeastern Minnesota. Assessment of the hydraulic properties of this aquifer continues to be of interest for wellhead protection and resource evaluation efforts. When performing constant-rate pumping tests on wells constructed in the karsted Prairie du Chien Aquifer, anomalous hydraulic responses resulting from cavernous flow are frequently observed. Hydraulic response in the adjacent Jordan Sandstone Aquifer is also commonly distorted because of bedding-plane fractures and well development techniques such as blasting and bailing. Resolution of these anomalous responses is important for accurate estimates of leakage through adjacent resistive layers. Examples are presented with a rational for the analysis process.