Deep Alluvial Aquifer Basin in Southern California: LWS has developed a surface water/ground water hydraulic interaction numerical model of a basin in Southern California using MODFLOW. The numerical model was developed after completing an extensive geologic model of the sediments in the basin. There is a concern related to contamination of municipal production wells by potentially responsible parties (PRPs) and, therefore, one of the objectives of the numerical model is to assess the fate and transport of constituents of concern in the aquifer from their source. Given that these are historical sources, they have been identified through the use of reverse particle tracking, using MODPATH.

San Luis Gold Project: As part of the permitting process related to the Tailings Storage Facility (TSF) LWS personnel used a MODFLOW model with MT3DMS to assess potential water quality issues should any water escape the TSF. The model was designed to specifically evaluate the attenuation of both flow and constituents of concern downstream as any theoretical release of water would exit an unnamed tributary of Culebra Creek where the TSF was located and flow into the Valley Fill aquifer. The Town of San Luis has two municipal production wells completed in the Valley Fill aquifer a few miles down gradient of where any theoretical release of water would enter the Valley Fill aquifer from the TSF. The model demonstrated that there would be no impact to the Town’s municipal production wells.

CF Industries Manufacturing and Distribution Facilities:  LWS personnel have prepared a number of ground water flow models related to assessing the fate and transport of fertilizer materials released to local ground water aquifers through operations and, in some cases, spills. Initial ground water investigations, including the installation of monitoring wells and collection of water quality data, have been conducted to develop the necessary information to then prepare ground water models to assess not only the fate and transport of constituents of concern (COCs) but also to identify issues related to regulatory agencies, e.g., containment of COCs within the property, attenuation of COC concentrations, and development of remediation actions. LWS personnel have assisted at sites in Tennessee, New York, Indiana, Illinois, Missouri, and Nebraska.