Application of VLEACH to Vadose Zone Transport of VOCs at an Arizona Superfund Site |
| |
| Authors: | J Rosenbloom P Mock P Lawson J Brown HJ Turin |
| |
| Institution: | Jeffrey Rosenbloom is a section chief in the Superfund Enforcement Branch in EPA Region IX. He has an engineering degree from the University of California at Berkeley. Rosen-bloom was the remedial projects manager for the Phoenix-Goodyear Airport NPL site.;Peter Mock is a senior hydrogeologist in CH2M Hill's Tempe, Arizona, office. He has a degree in hydrology from the University of Arizona. Mock was the project hydrogeologist for the Phoenix-Goodyear Airport NPL site.;Peter Lawson is a project hydrogeologist in CH2M Hill's Redding, California, office. Lawson holds a master's degree in hydrology from the University of Arizona. Lawson conducts a variety of modeling projects and coordinates use of the VLEACH model for CH2M Hill.;Jess Brown is a soil scientist in CH2M Hill's Redding, California, office. Brown has a degree in soil science from Humboldt State University. Brown led the vadose zone characterizations for the Phoenix-Goodyear Airport NPL site.;H.J. Turin is presently a research scientist at Los Alamos National Laboratories. Turin holds a master's degree in hydrology from the University of Arizona, and a doctoral degree from New Mexico Tech. Turin wrote and refined the VLEACH code while he was a hydrogeologist with CH2M Hill in Redding, California. |
| |
| Abstract: | Cleanup standards for volatile organic compounds in thick vadose zones can be based on indirect risk (transport to ground water) when contamination is below depths of significant direct risk. At one Arizona Superfund site, a one-dimensional vadose zone transport model (VLE-ACH) was used to estimate the continued transport of VOCs from the vadose zone to ground water. VLEACH is a relatively simple and readily available model that proved useful for estimating indirect risk from VOCs in the vadose zone at this site. The estimates of total soil concentrations used as initial conditions for VLF.ACH incorporated a variety of data from the site. Soil gas concentrations were found to be more useful than soil matrix data for estimating total soil concentrations at this arid-zone site. A simple mixing cell model was used with the VLEACH-derived mass loading estimates from the vadose zone over time to estimate the resulting changes in ground water concentrations. For this site, the results of the linked VLEACH/mixing cell simulations indicate it is likely that the federal MCI. for TCE will be exceeded in underlying ground water if remedial action on I he vadose zone is not pursued. |
| |
| Keywords: | |
|
|
