CSE has extensive experience with investigating and characterizing contamination of soils and groundwater. Our team has been involved in planning, field sampling, and data analysis phases of contaminant investigations at hundreds of sites across the New England region for a combined total of more than 40 years. Characterizing the magnitude and extent of groundwater contamination is a challenging task due to the limited locations from which subsurface data can be collected and to the dynamic nature of contaminant plumes as they migrate and degrade over time. A solid background in geology, soils, hydrology, and chemistry, along with applicable regulations and laboratory analysis methods, is needed to successfully delineate contamination. Understanding the nature and extent of contamination is an essential step in determining how best to reduce further impacts and to identify appropriate cleanup approaches. CSE applies the Conceptual Site Model (CSM) approach, which is a three-dimensional picture of site conditions that illustrates contaminant distribution, release mechanisms, exposure pathways, migration routes and potential receptors. The purpose of the conceptual site model is to present an understanding of known and suspect environmental conditions as they currently exist for the Disposal Site. The CSM also provides a basis for evaluating the need for implementing additional remedial actions.