CORRELATION BETWEEN DRASTIC VULNERABILITIES AND INCIDENTS OF VOC CONTAMINATION OF MUNICIPAL WELLS IN NEBRASKA

Because ft considers basic hydrogeologic variables believed to influen ce contaminant transport from surface sources to ground water, the DRA STIC method can be a valuable tool for identifying ground-water suppli es that are vulnerable to contamination. Theoretically, areas with hig h DRASTIC scores should have more frequent occurrences of ground-water contamination events than areas with low scores given similar land us e, well construction, and well densities. Relationships between DRASTI C scores and incidents of contamination, however, have not been extens ively documented. In Nebraska, significant positive correlation appear s to exist between incidents of VOC contamination of ground-water supp lied community water systems and the relative hydrogeologic vulnerabil ity of surficial aquifers as quantified with the DRASTIC method. These results provide a means of verifying the usefulness of planning tools such as DRASTIC for identifying areas where water supplies are most v ulnerable to contamination from surface sources.