Volatile organic compounds in ground water of the lower Illinois River basin

Water samples collected from 60 wells in the lower Illinois River Basin (LIRB) in 1996 were sampled and analyzed for 73 volatile organic compounds (VOC?s). There were only six VOC detections in more than 4,300 analyses of the ground-water samples: three detections of chloroform, one detection of carbon tetrachloride, one detection of methyl tert-butyl ether (MTBE), and one detection of 1,2,3,4-tetramethyl benzene (TeMB). VOC concentrations ranged from 0.22 to 4.7 micrograms per liter (?g/L), with only one VOC concentration greater than 1 ?g/L. A VOC was detected in one sample from the deep glacial drift aquifer, indicating that shallow aquifers may be more susceptible to VOC contamination than deep aquifers.