MODFLOW-2005 and MODPATH-6 Data sets of Simulated Groundwater Flow to Evaluate Wellbore Flow in Generic Long-Screened Wells Under Ambient Flow

A generic, three-dimensional finite-difference model, MODFLOW-2005 (version 1.12.00) and MODPATH-6 (version 6.0.01), was created to better understand the amount of vertical flow and cross-contamination of trichloroethene (TCE) that may be occurring in discontinued extraction wells under current (2018-19) ambient-flow conditions at site 25 of the Edwards Air Force Base, California. The wells are long-screened (100-ft long), contain a surrounding sandpack, and have not been pumped for approximately 10 years. The groundwater flow model utilized multiple observations made from the field measurements of flow and transport to conceptualize, calculate, and simulate in-well flow, and flow in the sand pack. The model was constructed to represent the average-flow condition near a typical long-screened well and was used to estimate flow in the sandpack and the wellbore and scenarios related to the hypothetical sealing of the interior of the well but leaving the sandpack intact. Relative estimates of vertical hydraulic conductivity between the wellbore and sandpack guided simulations. This study provided unique insights into ambient flow in long-screened wells set in low hydraulic conductivity aquifers that allowed for an improved assessment of remedial strategies to help mitigate cross-contamination of TCE. Understanding the dynamics of flow between the well and sandpack is needed to make informed decisions to mitigate contamination where the wellbores are facilitating the spread of contaminants through cross contamination under ambient-flow conditions. Three simulations were done including a simulation with no well, a simulation with the well open and unpumped with a surrounding sandpack, and a simulation with the well sealed with a liner but the sandpack left intact. Further information on the generic model is described in the journal article (https://doi.org/10.1007/s12665-024-11828-3). This USGS data release contains all the input and output files for the simulations described in the associated journal article.

                                            [
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                                            {
  "fn": "Philip T. Harte",
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