UC Santa Barbara

The application of correction factors to measured ground-water elevations is an important step in the process of characterizing sites contaminated by petroleum products such as gasoline. The water-table configuration exerts a significant control on the migration of free product (e.g., gasoline) and dissolved hydrocarbon constituents. An accurate representation of this configuration cannot be made on the basis of measurements obtained from monitoring wells containing free product, unless correction factors are applied. By applying correction factors, the effect of the overlying product on the apparent water-table configuration is removed, and the water table can be analyzed at its ambient (undisturbed) level. A case history is presented where corrected water-table elevations and elevations measured at wells unaffected by free product are combined as control points. The use of the combined data facilitates a more accurate assessment of the shape of the water table, which leads to better conclusions regarding the source(s) of contamination, the extent of free-product accumulation, and optimal areas for focusing remediation efforts.© ASCE.