Services Rendered:

FRAC3D Groundwater Model

PTRAX Particle Tracking Model

Hydraulic Conductivity Assessment

Grain Size Analysis

P²T (pre-cursor to DSI) integrated geological, hydrological, chemical, and meteorological data into a conceptual model of groundwater flow and movement of contaminants in the area adjacent to the Entomology Shop at LAFB. Initially P²T was tasked to develop a porous media type numerical groundwater flow model. Through the conceptual model development process, P²T determined that fracture flow is probably a dominant flow mechanism and that a numerical model which simulates flow and transport through fractured media would more accurately represent site conditions. In order to address the study objectives and to meet the original scope of efforts, P²T determined that two groundwater models must be developed. One model assumes a porous media dominated groundwater flow system while the other assumes a fracture flow dominated system (in the area of the TCE plume). The porous media model addresses the bulk movement of groundwater flow but is lacking in that it cannot accurately represent flow or contaminant movement through the fractured bedrock at LAFB. The fracture flow model was developed to more accurately reflect the site conceptual model. A concern relative to the fracture flow model is that there is limited information on which to define the fracture system in the area of the Entomology Shop. Both the porous media and fracture media flow models were simulated using the FRAC3DVS groundwater code. Solute transport was simulated using the particle tracking code PTRAX to illustrate the impact of alternative remediation options as well as fractured flow on the migration of TCE. The following figure shows the coarse scale model with Water Residence time analysis and Deposition Erosion map