IMPROVING THE DESIGN OF IN SITU BIOREMEDIATION IN FRACTURED BEDROCK THROUGH 3D VISUALIZATION AND ANALYSIS

Previous operations at a former industrial site have contributed chlorinated volatile organic compounds (VOCs) to a mixed, 120-acre plume. The source area plume exists in both the overburden and bedrock aquifers with the majority of mass transport from the site occurring through the fractured shale bedrock. An in situ bioremediation program was implemented in the source area in both the overburden and bedrock aquifers. Earth Volumetric Studios (EVS) software was utilized in order to gain a better understanding of the bioremediation performance. EVS software uses advanced gridding and geostatistical analysis to create 3D models of geologic setting and analyte spatial data.

Using well boring logs, geophysical data, and downhole bedrock logging, the geologic model of the source area overburden and bedrock lithology was constructed in EVS. Groundwater chemistry data generated representative chlorinated VOC plumes by applying krigging techniques in EVS. A fluorescent tracer test was also modeled to better illustrate preferential pathways. Following the injections of two fluorescent dyes, time-series models were generated in order to document the morphology of the dyed groundwater plumes.

Simultaneous display of both the geologic and dye plume models within EVS visually illustrated tagged groundwater migration along fractured bedding-plane partings, tectonic fractures, position of subcropping discrete fracture zones with respect to source areas and injections, and the lithologic influence on plume geometry. Plume models were also generated for the chlorinated VOCs in order to design an effective in situ bioremediation remedy for bedrock and overburden. The ability to display volumetric plume models within a 3D geologic model provided a powerful tool for assessing hydrogeologic conditions promoting/inhibiting the remediation of the chlorinated VOC source area plume.