Objective:

The objective of this demonstration is to evaluate the capabilities of the Natural Attenuation Software (NAS) to provide reasonable estimates of cleanup times associated with combining source-area remediation with Monitored Natural Attenuation (MNA). The tool will be evaluated using data from six to eight sites throughout the United States that encompass diverse geologic and hydrogeochemical environments. By comparing the predictions from early data sets to empirical data during the predicted period, the utility of the estimates will be assessed. A performance report will be developed to document the conditions and metrics for these sites.

Technology Description:

The NAS tool is designed for application to groundwater systems consisting of porous, relatively homogeneous, saturated media such as sands and gravels. It specifically targets petroleum hydrocarbon and chlorinated ethene contaminants. First, detailed site information about hydrogeology, redox conditions, and contaminant concentrations must be entered. After data entry, NAS estimates a range (maximum, minimum, and best estimates) of site-specific groundwater flow rates, biodegradation rates, and sorption properties. Based on these estimates, NAS then produces either analytical or numerical solutions for time of remediation (TOR) based on site-specific remediation objectives. The analytical solutions are specific to plume temporal and spatial dynamics, such as the distance of stabilization for given source-area contaminant concentrations and the time for plume stabilization when source-area concentrations are changed (i.e., removal actions). In the case of non-aqueous phase liquid (NAPL) sources, NAS implements the SEAM3D solute transport model to estimate TOR for a given NAPL mass to dissolve and lower contaminant concentrations at the source area below a given user-supplied threshold. Further information on the NAS tool and a copy of the software are available at http://ceeweb.cee.vt.edu/nas/.

Expected Benefits:

To date, cost estimates associated with MNA have not been based on reliable estimates of remediation timeframes. With the validation of NAS at a variety of sites, improved estimation of capital and operations and maintenance (O&M) costs is achievable. When the NAS tool is combined with cost assessment tools, Department of Defense (DoD) Remedial Project Managers can develop optimization strategies, employing cost-benefit analyses that compare MNA to engineered remedial actions or combinations of remedial actions and MNA. (Anticipated Project Completion - 2006)

Principal Investigator:

Dr. Mark Kram

Naval Facilities Engineering Service Center

1100 23rd Avenue, Code 413

Port Hueneme, CA 93043

Telephone: (805) 982-2669

Fax: (805) 982-4304

E-mail: mark.kram@navy.mil