Gradient

Chemical Fate & Transport

Overview
Example Projects
Experts

Overview

Gradient's extensive expertise in chemical fate and transport analysis helps our clients interpret complex environmental data and/or predict chemical concentrations when data are not available. Whether using detailed physical/biogeochemical models, data-driven mass balance approaches, or more complex hybridized techniques, we excel at identifying the most effective combination of modeling and data analysis to solve even the most complicated fate and transport questions.

Fate and Transport

Example Projects

PCE Groundwater Modeling for a Conceptual Remedy Design

Full Description

Gradient developed a conceptual design of a groundwater pump-and-treat remedy using a 3-D numerical groundwater contaminant transport model that was calibrated using 10 years of existing groundwater quality data. We used the model to develop an optimal remedial system design, which was ulimately selected for implementation.

Multi-pathway Transport Analysis in a Property Damage Case

Full Description

Gradient assessed a property damage claim alleging impacts due to releases from a chemical manufacturing plant by evaluating pesticide and dioxin occurrence patterns and transport mechanisms via multiple pathways. We reviewed potential plant-related sources in the context of a regional conceptual model for chemical transport and compared data from other sites in the US, including sites where there were no nearby manufacturing plants.

Post-remedy Recontamination

Full Description

Gradient reviewed post-remedy data for PCBs and a chlorinated DNAPL in brook sediments and the floodplain at a Superfund site to determine the need for additional remediation. We assessed whether the contaminants in sediments posed a risk to human health and the environment. We also evaluated the transport mechanisms responsible for the recontamination of previously excavated areas.

Human Health Risks from Chlorinated Organics Vapor Intrusion

Full Description

Gradient evaluated vapor intrusion-related risks associated with chlorinated organics contamination in soil and groundwater identified during the five-year remedy review of a Superfund site. We modified US EPA's vapor intrusion model to predict on-site, indoor air concentrations of PCE and TCE and quantified a range of potential health risks to facility workers.

Source and Plume Evaluation for an Insurance Recovery Claim

Full Description

Gradient evaluated sources, release timing, and fate and transport of chlorinated solvents, PCBs, and other contaminants in the subsurface in the vicinity of a 600-acre former industrial facility, focusing on contributions to a regional, 2.5-mile long groundwater plume. We reviewed environmental investigations and other records dating back to the 1940s to develop a conceptual model of contaminant release and migration in groundwater.

Evaluation of Benzene Exposure

Full Description

Gradient assessed claims of benzene exposure by residents living adjacent to a former refining facility. We reviewed analytical data from previous subsurface environmental studies and assessed vapor intrusion potential from groundwater quality data. We also evaluated benzene exposure from an epidemiological perspective and compared exposure risks relative to ambient air from other urban areas.

Experts

Andrew B. Bittner Read Bio

Samuel A. Flewelling Read Bio

Kurt Herman Read Bio

David E. Langseth Read Bio

Laurent C. Levy Read Bio

David E. Merrill Read Bio

Jeffrey T. Rominger Read Bio

Manu Sharma Read Bio

Meghna H. Swamy Read Bio

Matthew P. Tymchak Read Bio