MODFLOW-NWT and MODPATH5 models used to identify potential flow paths from San Juan Mine to hydrologic receptors, San Juan County, New Mexico

Coal combustion by-products (CCBs, in the form of ash) produced at the coal-fired San Juan Generating Station in San Juan County, New Mexico, have been buried in former surface-mine pits at the San Juan Coal Mine since power-generation operations began in the early 1970s. A groundwater flow model was developed by the USGS to estimate the timing of groundwater recovery after the cessation of mining and to identify potential pathways and advective travel times for groundwater transport of metals that may be leached from stored CCBs to arrive at hydrologic receptors after mining operations cease. The USGS numerical modeling package MODFLOW-NWT with MODPATH particle-tracking software was used. This USGS data release contains all of the [...]