ASTM D5850-20 PDF Download

ASTM D5850-20 is a standard practice that provides an analytical procedure for determining the transmissivity, storage coefficient, and anisotropy ratio of a confined aquifer. The practice utilizes observation well drawdown measurements from a constant-rate pumping test. The procedure requires a minimum of four partially penetrating observation wells to be positioned around a partially penetrating control well.

The standard assumes certain conditions, including: the control well discharges at a constant rate, the control well is of infinitesimal diameter and partially penetrates the aquifer, data are obtained from partially penetrating observation wells at different elevations, the aquifer is confined, homogeneous, and areally extensive, and the discharge from the well is derived exclusively from storage in the aquifer.

The calculation requirements of the method are computationally intensive, and it is recommended to use computerized procedures or mathematical software for evaluating the required functions. The standard also emphasizes the importance of competent personnel, suitable equipment, and facilities in ensuring reliable results.

The limitations of this practice are related to the correspondence between the field situation and the simplifying assumptions made in the practice. The standard also provides guidelines for significant digits and rounding of observed and calculated values.

It is important to note that this ASTM standard is not intended to replace professional judgment or the standard of care in assessing the adequacy of a given professional service. The document should be used in conjunction with education, experience, and consideration of the unique aspects of each project.