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BioTrends DESCRIPTION Evaluation of Natural Attenuation Trends BioTrends
provides an integrated suite of tools for conducting natural
attenuation trend analyses, calculating first-order degradation
rates, calculating the natural attenuation "score" for your site,
and conducting groundwater modeling to predict pollutant plume
attenuation. These tools are combined with a comprehensive
data management system to provide a powerful and easy-to-use platform for
evaluating Monitored Natural Attenuation.
BioTrends is especially useful when applied to quantify the
efficacy of natural attenuation, and also to compile and analyze the
long-term monitoring data that must be collected to ensure the
reliability of this remedy once it has been
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Once the
required site data has been collected, the next step in a natural
attenuation assessment is to evaluate the spatial and temporal
trends for priority pollutants and geochemical indicators. Key
questions that need to be answered include:
These questions are critical when evaluating whether natural
attenuation is an effective remedy. That's why BioTrends was
specifically designed to provide you with the tools you need to
determine whether Monitored Natural Attenuation is a viable
alternative for your site.
For example, you can take advantage of the dynamic link between
the chart tools and the project database to quickly plot an x-y
chart of concentration vs. distance along a primary flowpath
downgradient from a source area. Just select the wells included in
the flowpath, select the chemicals and monitoring events to be used
for each data series, and the program will do everything else for
you including extraction of the analytical data from the project
database; automatic calculation of unit conversions (if necessary);
and creation of the plots using "smart chart" tools specifically
designed to work with chemical analytical data.
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Or use
another tool to plot an x-y chart of concentration vs. time by
simply defining the chemicals, monitoring wells, and monitoring
events you want to see on the chart. It's that easy! You can define
any number of data series to view on the charts, and you can easily
change the appearance of the lines and symbols for each data series.
"Non-detect" data is plotted using any of the chart tools
included with BioTrends. You have the option of using a unique
symbol shape and color to represent non-detect data in any of the
chart data series. This allows you to instantly see data on the
chart that represents a "non-detect" measurement which can be
particularly useful when working with samples that were
significantly diluted. For example, a pollutant method detection
limit (MDL) for a contaminated groundwater sample may be as high as
10,000 ug/L. Using the special non-detect symbol makes it obvious
when a chemical was not detected during an analysis - otherwise, the
data shown on the chart makes it appear that the chemical was
measured at a concentration of 10,000 ug/L at that location. Often it
becomes necessary to calculate first-order degradation rates for
priority pollutants. These rates are used to determine how far
down-gradient the contaminated groundwater may migrate before
becoming stable in time. The EPA chlorinated solvents natural
attenuation protocol (Wiedemeier et al., 1998) defines two methods
that may be used to calculate first-order rates:
Both these
methods involve a number of calculation steps that can be cumbersome
and time-consuming, particularly when you have to recheck your
calculations or redo them entirely using slightly different data.
The data analysis tools included with BioTrends make it extremely
simple to calculate first-order rates using either of these methods.
These tools allow you to calculate pollutant degradation rates
between a pair of monitoring wells or average rates along a flowpath
of wells using a log-linear regression analysis.
All you have to do is:
BioTrends will automatically go through all the calculation steps
for you and will allow you to change any input parameters so you can
assess the sensitivity of the final rate calculations to input
parameters which may be uncertain. By integrating these calculation
tools with the project database, the effort you have to expend is
minimal, the potential for error when making these calculations is
reduced significantly, and the time savings can be used to conduct a
more thorough sensitivity analysis to determine a range of potential
degradation rates given the uncertainty in your input
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Click Here For More Information On Calculating Degradation Rates 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.
Click Here For Information On The Project DMS Click Here For Information On SEQUENCE Click Here For Information On BioTracker 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.
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