Micro‐Purge Low‐Flow Sampling of Uranium‐Contaminated Ground Water at the Fernald Environmental Management Project

Abstract

AbstractEfforts to sample representative, undisturbed distributions of uranium in ground water beneath the Fernald Environmemal Management Project (FEMP) prompted the application of a novel technique that is less invasive in the monitoring well. Recent studies (Kearl et al. 1992; Barcelona et al. 1994) indicate that representative samples can and should be collected without prior well volume exchange purging or borehole evacuation. Field experiments conducted at the FMMP demonstrate that under specific sampling conditions in a welldefined hydrogeologic system, representative ground water samples for a monitoring program can be obtained without removing the conventional three well volumes from the well. The assumption is made that indicator parameter equilibration may not be necessary to determine when to collect representative samples at the P'liMP. Preliminary results obtained from the field experiment suggest that this may be true. The technique employs low purge rates (< 1 L/min) with dedicated bladder pumps with inlets located in the screened interval of the well, while not disturbing the stagnant water column above the screened interval. If adopted, this technique, termed micro‐purge low‐flow sampling, will produce representative ground water samples, significantly reduce sampling costs, and minimize; waste water over the monitoring life cycle at the FEMP. This technique is well suited for sites that have been fully characterized and are undergoing long‐term monitoring.