Reconstructed Plume Method for Identifying Sources of Chlorinated Solvents

Abstract

This article discusses a method for identifying sources of chlorinated solvent releases without the need to formulate site-specific degradation rates. Instead, converting measured concentrations of daughter products to equivalent concentrations of parent products furnishes the needed information. The method is illustrated with a case study, and consists of two parts: 1) developing a picture of what the plume would have looked like if biodegradation and hydrolysis had not occurred, and 2) factoring in what is known about groundwater flow direction. The relevance of this method for identifying areas where biodegradation has occurred and for age-dating plumes is also discussed.

Keywords:

• chlorinated solvents
• source identification
• anisotropic kriging
• age-dating plumes

Notes

¹For example, 23 of 41 sites in EPA's vapor intrusion database have TCE (US EPA 2008). The chemical with the second highest number of sites is PCE with 14. The TCA breakdown product 1,1-dichloroethylene is found at eight of the 41 sites.

¹New Jersey Department of Environmental Protection, 2005);

²Assuming fraction of organic carbon (foc) = 0.002, porosity (n) = 0.3, bulk density (ρ b) = 1.7;

³TCE is the parent for cis- and trans-1,2-DCE; vinyl chloride and TCA form the parent for 1,1-DCE, 1,1-DCA and chloroethane.