Geophysical Well Logging And Discrete Depth Water Sampling Methods To Identify Sources Of Elevated Barium In A Water Well In Northern Illinois

A geophysical logging study was conducted on a municipal water well in the City of<br>Sycamore, Illinois. The purpose of the study was to identify the source of elevated barium<br>levels in the well and determine if the well could be reconstructed to reduce barium<br>concentrations without significant loss in production. The geophysical logging suite<br>included a downhole televising log, four arm caliper log, gamma ray log, dual induction<br>log, gamma density log, and neutron density log. In addition, a spinner flow meter log<br>was conducted while pumping and water samples were collected from the pumping water<br>column at discrete depths. The results of the logging study indicated that the majority of<br>the barium was entering the borehole from the lower portion of the well which appeared<br>to be producing only about 15 to 30% of the total water production. The lower portion of<br>the well was sealed off with a neat cement grout plug. Barium concentration was reduced<br>by over 50 % with a reduction in specific capacity of about 30 to 40%. While the logging<br>study was successful at identifying the high barium interval, the longevity of the barium<br>reduction is a function of the vertical isolation provided by the confining units in the<br>aquifer.