Natural Attenuation "Score"
The EPA technical protocol for the natural attenuation of chlorinated solvents (Wiedemeier et al., 1998) presents a screening process that can be followed to provide a preliminary assessment of whether natural attenuation may be an effective remedy for a site. Although there are many factors which contribute to the overall performance of natural attenuation, it is sometimes helpful to perform a quick calculation of the natural attenuation "score" for a site. The higher the score, the more suitable natural attenuation is likely to be as a groundwater remedy.
The tool provided in BioTrends for calculating this natural attenuation score is also linked to the project database. So all you have to do is define the scope of the database search criteria (i.e., which monitoring stations and monitoring events to use for determining the min/max concentration values for specific chemicals) and specify how non-detect data should be handled. The program will then search the database and automatically calculate the natural attenuation "score" for your site by comparing measured chemical concentrations to the criteria defined by Wiedemeier et al., 1998. The only other step you have to do is specify whether various chlorinated solvents are present as daughter products at the site - the score will then be changed accordingly.
BioTrends comes with a simple screening tool that can be used for modeling three-dimensional advection-dispersion-degradation-sorption in groundwater using BIOSCREEN (Newell et al., 1996). BIOSCREEN is a simple spreadsheet analytical model that has been made available in the public domain. You can run this model simply by selecting the BIOSCREEN option from the BioTrends Menu.
If your modeling needs are more sophisticated than the representation provided with BIOSCREEN, you may want to consider using BioTracker, an innovative new screening model that provides unique visualization tools for evaluating and documenting natural attenuation modeling results. BioTracker is based on a numerical model (BioRedox) so it can be used to provide a more site-specific representation of the biodegradation reactions. For example, BioTracker can simulate sequential transformations for any number of chlorinated solvent or radio-nuclide parent-daughter species, and it can also simulate the accumulation of a halogen such as chloride with each reductive dechlorination reaction. Simulating halogen accumulation is an important feature when calibrating a sequential transformation model to observed field conditions.
Buschek, T.E. and C.M. Alcantar, 1995, Regression Techniques and Analytical Solutions to Demonstrate Intrinsic Bioremediation, in proceedings of the 1995 Battelle International Conference on In-Situ and On Site Bioreclamation, April 1995.
Newell, C.J., R.K. McLeod, and J.R. Gonzales, 1996, BIOSCREEN Natural Attenuation Decision Support System - User's Manual, United States Environmental Protection Agency, Report EPA/600/R-96/087, August 1996.
Wiedemeier, T.H., M.A. Swanson, D.E. Moutoux, E. Kinzie Gordon, J.T. Wilson, B.H. Wilson, D.H. Kampbell, P.E. Haas, R.N. Miller, J.E. Hansen, and F. Chapelle, 1998, Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Ground Water, United States Environmental Protection Agency, Report EPA/600/R-98/128, September 1998.
BioTrends includes a comprehensive user's manual containing easy-to-follow instructions and step-by-step tutorials to guide you through the process of creating a project database and using the data analysis tools.
BioTrends Hardware Requirements
PC Pentium (100 MHz)
32 MB RAM
25 MB free disk space
SVGA display and mouse
Windows 95/98/2000 or NT installed