MODFLOW-NWT and MODPATH6 model use to analyze remedial scenarios affecting plume movement through a sole-source aquifer system, southeastern Nassau County, New York

A three-dimensional steady-state groundwater flow model is coupled with the particle-tracking program, MODPATH, to assess the fate and transport of volatile organic compound plumes within the Magothy and upper glacial aquifers in southeastern Nassau County, NY. Knowledge of groundwater-flow patterns and rates is essential for effective management of groundwater resources and for mitigation of potential adverse effects of the plumes on drinking-water supplies and on ecosystems. Eight hypothetical remedial scenarios were evaluated to hydraulically contain a VOC plume. Specifically, the remedial scenarios were optimized to achieve full containment by altering the pumping well locations, adjusting the pumping rates, and adjusting the discharge locations and rates. This modeling analysis will allow the New York State Department of Environmental Conservation (NYSDEC) to evaluate pump-and-treat remedial alternatives identified in a separate feasibility study (FS), including plume containment and hydrologic effects. Modeling will also provide insight into the potential impact to the environment that remedial alternatives may have. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20205090).