Effect of Groundwater Table Fluctuations on Hydrocarbon Thickness Measurements
Mustafa M. Aral and Boshu Liao
Multimedia Environmental Simulation Laboratory
School of Civil and Environmental Engineering
Georgia Institute of Technology
Atlanta, Georgia 30332
Abstract
In hydrocarbon contaminated sites, it is common practice to collect hydrocarbon thickness measurements from monitoring wells. This data is later used in computer models to estimate the total hydrocarbon volume at these sites during various stages of remediation. The purpose of this effort is to estimate or evaluate the efficiency of the overall remediation process at a particular site. In most cases, the data obtained from this analysis show significant variations in total volume estimates over time. This may imply that the assumptions used in relating the monitoring well hydrocarbon thickness measurement data to the formation hydrocarbon volume may not be representative of the conditions at the site. In this paper we investigate the effect of groundwater table fluctuations in an unconfined aquifer, on the hydrocarbon measurements in a monitoring well using analytical methods. Our findings indicate that, under fluctuating groundwater table conditions, if the total volume estimates in the formation are based on monitoring well measurement made at one point in time, or if these estimates are based on a sequence of measurements made over a period of time which are than evaluated independently, the volume estimate results will be in significant error.