Surface geophysical surveys (electromagnetic) were used to reduce the cost, and increase the effectiveness of the assessment and remediation of a conductive ground water plume in Michigan. Following the release of an estimated 50 bbl. oil and 800 bbl. brine from a pipeline rupture, an inexpensive electromagnetic (EM) geophysical survey was performed to help define the areal extent and configuration of impacted ground water. Test borings, monitor wells, and an interceptor drain system were installed based on the results of the EM survey. Remediation is being accomplished by pumping impacted ground water from the drain and injection of the purged water into a Class IIR secondary recovery injection well.
Throughout remediation, quarterly EM surveys have been used to demonstrate progress. Over the three year remediation period, the chloride concentration in the most contaminated monitor well has been reduced by 99.7%, from 68,000 to 200 milligrams/liter (mg/l). The highest apparent conductivity in the plume has been reduced by 84.5%, from 290 to 45 millimhos/meter (mmho/m).