Site Assessment and Investigations

EA’s engineers are extremely knowledgeable in proven and innovative assessment methods to determine the quality of soil, soil vapor, ambient air, groundwater, unsaturated zone pore fluids, and surface water. EA has designed and executed subsurface characterization approaches from minimally intrusive investigations to full RCRA/CERCLA-based remedial investigations. These investigations delineate the nature and extent of environmental impacts in soil, soil vapor, groundwater and/or surface water, including dense and light non-aqueous phase liquids. EA staff utilizes targeted information collection methods to reduce long-term commitments and often unnecessary data collection efforts.   

EA’s staff are well versed in assessing vapor intrusion potential through screening level evaluations, predictive models, and empirical data sets. EA has implemented many indoor air assessment projects for industrial, commercial, and residential properties under the oversight of Regional Water Quality Control Board (RWQCB), Department of Toxic Substances Control (DTSC), and U.S. Environmental Protection Agency (EPA). EA’s staff have prepared assessment work plans incorporating use of soil vapor, sub-slab, and indoor air sampling programs.

EA staff have developed many conceptual site models (CSM’s) for projects in multiple states to support site assessment and remediation strategies, fate and transport models, human health and ecological risk assessments, vapor intrusion evaluations, and groundwater basin water supply studies. Many of the CSM’s have been reviewed by oversight agencies including EPA, DTSC, RWQCB, etc. as well as technical peer review committees. The CSM’s have included complex weathered/fractured bedrock systems, epikarst/karst systems, complex structural deformation of sediments, and regional groundwater basins covering areas of over one hundred square miles.

EA’s engineers have prepared and managed groundwater flow, vadose zone, and surface water flow contaminant transport models for numerous projects in various phases at CERCLA, RCRA and state-lead sites. EA has extensive experience modeling contaminant conditions for soil, groundwater, and surface water while assessing their fate and transport in these media. This experience has taught us the importance of matching the model and overall strategy to the goals of the modeling effort at the beginning of the process to save money and time. Often, simple models can achieve the project objectives but when more complex models are necessary, EA has the experience to identify the model that will produce the most accurate results.

EA staff have prepared public participation plans, community surveys, community notices, responses to frequently asked questions and to community inquiries. EA has also established document repositories and toll-free information hot-lines for the public. In addition, EA has prepared and transmitted public outreach communications to state senators, legislators, governors, and other state and local officials, community and environmental groups, and nearby residents.