Gulf Coast Refinery 3D LNAPL Conceptual Model

Using Models to Evaluate Performance

Client

Confidential Client

Location

Southeast Texas

Key Elements

Comprehensive 3D LNAPL conceptual model
Visualization of remedy success for effective communication with regulators
Complex geology and hydrogeology

GEI constructed a 3D LNAPL conceptual model incorporating decades of data to illustrate the geology, hydrogeology, contaminant extent, and effect of the existing remedy for a large and complex site.

The model was used to evaluate the performance of an ongoing remedy as well as to illustrate the results of the evaluation to the site regulator. It continues to be used as a live model for evaluation of new projects or potential issues as site conditions change.

The site has a complex geology and hydrogeology as well as multiple historic releases on-site that are commingled with off-site sources. A new approach was needed to incorporate decades of data of various types and sources into a single tool for an effective evaluation. The geology, hydrogeology, and contaminant extent were modeled incorporating over 5,700 well gauging data points from 162 monitoring and recovery wells.

The model included over 65,000 individual CPT data points and over 75,000 LIF data points from 101 borings. Over 14 years of monthly groundwater and hydrocarbon recovery data from up to 108 recovery wells was also utilized. GIS data such as underground pipeline corridors, historical contour maps of potentiometric surface, groundwater contaminant extent, LNAPL extent, and LNAPL transmissivity were also added to the model. Likewise, basemaps and aerial photos were incorporated to provide scale and orientation to the visualizations.

Results

The model provided a visual representation of the complex geology and hydrogeology of the site, which leads to exaggerated thicknesses of LNAPL in wells that are not indicative of the recoverability of the LNAPL. The model was then utilized to evaluate where and why the exaggerated thicknesses occurred as critical component of a demonstration that the existing remedy had sufficient coverage, both laterally and vertically, to achieve the remedy goals for the site.

Images, cross-sections, and movies constructed from the model were incorporated into a presentation and meeting with the site regulator. GEI and the client were successful in demonstrating the success of the remedy to the regulating agency.

The client continues to support incorporating additional site data into the model as it is collected and maintaining it as a live tool to use for ongoing and future projects.

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well gauging data points

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monitoring and recovery wells

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individual CPT data points