Three-dimensional (3D) visualizations can provide powerful analytical capabilities in addition to “pretty pictures”. 3D visualization is particularly useful in conjunction with detailed microstratigraphic investigations (e.g., CPT), vertical Light Non-Aqueous Phase Liquid (LNAPL) impact profiles (e.g., laser induced fluorescence [LIF]), long-term equilibrium well gauging data, well construction data, and detailed topographic surveys. While many factors control LNAPL distribution and migration potential, perhaps none is more important than microstratigraphy.
The capillary properties of thin stratigraphic horizons may be sufficient to either facilitate or inhibit LNAPL movement through the soil. A microstratigraphic investigation (e.g., CPT) can identify such layers, and greatly facilitate understanding of the LNAPL conceptual site model (LCSM). Macro-analysis of the microstratigraphic data can provide a broader understanding of critical stratigraphic geometries (e.g., LNAPL “traps” in high spots on the base of confining layers). The addition of LNAPL impact profiles (e.g., LIF) can provide an understanding of the distribution and historical migration pathways of LNAPL through the soil profile within the microstratigraphic setting. Long-term equilibrium gauging data provides a tool to evaluate the hydrogeologic conditions of the LNAPL (e.g., perched, confined, unconfined LNAPL), and data to identify critical surfaces (e.g., minimum historical NAPL/water interface elevation by well, which provides an estimated lower limit of the occurrence of mobile LNAPL). Well construction and topographic data allow analysis of critical areas such as potential surface seeps.
All of this data can be combined into various types of 3D visualizations that can be rotated and sliced in any direction to better understand the 3D relationships of microstratigraphy, LNAPL distribution, and groundwater elevations. Critical areas of the 3D blocks may be zoomed in to explore in detail the micro-scale stratigraphic variations critical to understanding LNAPL distribution and migration potential. A stronger LCSM leads to better remediation design and optimization decisions.