ERS has completed Remedial Investigations for 19 Department of Defense landfills, and assessed the feasibility of various approaches to reduce risks posed by these landfills. ERS’ approach to the characterization of these landfills was highly successful in employing multiple investigation methods to reduce the uncertainties that can result in unnecessarily high remedial costs.
For example, high-resolution topographic relief maps were created using LIDAR imaging (Light detection and ranging). These images were a useful tool to identify locations and boundaries of landfills as well as investigation areas for unidentified landfills. Historical trenching operations and differential settling associated with landfill contents can be identified with LIDAR imaging regardless of vegetation that often renders aerial photography ineffective.
ERS conducted geophysical investigations using frequency domain electromagnetic induction (FD-EMI) to differentiate the pit fill material from native soil and adjust boundary locations. Additional geophysical methods that ERS has used in landfill investigation include, ground penetrating radar, magnetic surveys, DC resistivity arrays, and multichannel seismic methods. Following non-intrusive investigations, the boundary, cover, and contents of the landfills were then confirmed by drilling and/or excavated test pits and sampling.
ERS personnel also have experience in conducting soil gas sampling at landfill sites. ERS has effectively employed numerous soil gas sampling and screening methods to delineate the extent of volatile chemicals. ERS places emphasis on soil gas screening methods using PID, ECD, or membrane interface probe (MIP) technologies to generate in situ results that guide sampling efforts and drive down costs. These comprehensive investigation techniques have allowed us to successfully close landfill sites without unnecessary removal of contents that do not pose a risk to human health or the environment.