For site remediation projects, one of the primary goals of data interpretation and visualization is to determine the efficacy of the remediation methods being used. When environmental contaminant data are interpreted and visualized, it provides decision makers with the information they need to make environmentally sound choices that will lead to remediation of the contaminated site. One of the best methods is to estimate the contaminant mass that is removed as a result of the remediation methods being used. There are various approaches to calculating contaminant mass in groundwater and soil. They range from very simplistic calculations that use many assumptions to very detailed methods that employ as much site-specific data as is available. For example, Battelle scientists recently reviewed site-specific contamination data for a government client interested in assessing the effectiveness of remediation approaches at several sites.

Battelle scientists used EarthVision^TM modeling and visualization software by Dynamic Graphics, Inc., to generate 3-D grids for these sites. Isoshells, which are concentration contours in 3-D space, define volumes within specified concentration ranges. The average concentration of this range is used to calculate the contaminant mass located within that volume. This calculation is performed using a spreadsheet and incorporates a site sediment porosity for groundwater and a dry bulk density for soil contaminant mass estimates.

As is customary in most studies of the effectiveness of remediation technology, the mass estimates were determined by using pre- and post-remediation data sets. At one site, Battelle developed a before and after contaminant mass estimate in groundwater at a site contaminated with chlorinated hydrocarbons. The primary chemical of concern (COC) is trichloroethene (TCE). The data showed a greater percent reduction in the first month than in the following three, indicating a diminishing return with respect to mass removal over time.

At another site, Battelle is investigating the efficacy of soil vapor extraction for soil remediation. TCE is once again the primary COC. This site also shows a diminishing removal rate, demonstrating that the remaining contamination is not being removed as quickly as earlier in the process.

Responsible parties and regulators can use this mass calculation data, along with the associated visuals, to make future decisions on how best to complete remediation at these sites. Different methods may be more effective at removing residual contamination than the technologies used initially to remove or decompose the bulk of the contaminant.

For more information on Battelle’s capabilities for site data evaluation, contact Jim Hicks at (614) 424-3958, hicksj@battelle.org.