API PUBL 4730:2003 pdf download
API PUBL 4730:2003 pdf download.Groundwater Remediation Strategies Tool.
4.0 TOOLS FOR ESTIMATING REMEDIATION LIFETIMES
To estimate the source lifetime for use in soil and groundwater modeling, two general approaches can be used (Farhat et al., 2002):
• Extrapolate concentration vs. time trends. This can be done either for natural attenuation processes, or for a remediation system. However, several years of monitoring data are required to get a trend that is robust enough to be useful.
• Use massbased source models to estimate remediation timeframes. With a source mass estimate and the mass flux leaving the source, an estimate of the time required to actneve a remediation goal can be estimated. This is the only method that will provide information on the impact of proposed remediation measures (i.e., trend data before a remediation system is installed will not provide any information on the remediation timeh-ame of the system). Note that there is considerable uncertainty with estimating mass and remediation timeframes using this method, and that the final answers will likely be an order- of-magnitude endeavor.
This section provides a list of references, resources, and tools for estimating remediation timetrames.
4.1 Key Resources – Books
Natural Attenuation of Fuels and Chlorinated Solvents, (Wiedemeier, et al. 1999). Source mass estimation and simple models for source decay are presented In Chapter 2, Attenuation of Sources and Formation of Plumes.
4.2 Key Resources – Data Interpretation Methods
Aqueous Concentration Ratios to Estimate Mass of Multi-Component NAPL Residual in Porous Media. (Feenstra, 1997). This method uses the preferential dissolution of the more soluble components in a multi- component NAPL to estimate NAPL mass.
“Estimation of Residual Dense NAPL Mass by Inverse Modeling”, (Butcher and Gauthier, 1994). This paper presents a method and equations for estimating NAPL mass at a site on the measured flux of dissolved contaminants leaving the source zone.
4.3 Key Resources – Models
SourceOK Remediation Timetrame Decision Support System (Farhat et al., 2002). This public-domain tool contains both utilities for estimating source mass from soil and groundwater data and simple models for estimating remediation timeframes.
Evaluating Hydivcarton Removal from Source Zones and its Effect on Dissolved Plume Longevity and
Magnitude: Tools to Assess Concentration Reduction (Huntley and Beckett, 2002). This document summarizes LNAPL source zones and provides a computer tool, LNAST, to evaluate the potential benefit of source removal.
BIOSCREEN User’s Manual (Newell et al., 1996). This manual reviews a simple box model for evaluating source decay.
State of Floncla Natural Attenuation Decision Support System (Groundwater Services, Inc. 1 997b). This proprietary software contains utilities for estimating source mass from soil and groundwater data.
4.4 Key Resources – Field Tests
“Sensitivity models and design protocol for partitioning tracer tests in alluvial aquifers”, (Jin et al., 1997). This paper provides a design protocol for performing partitioning tracer tests and discusses potential interferences with the procedure.
6.1 How to Use the Mass Flux vs. Distance Curves
The goal for using these curves is to evaluate how long it takes an upgradient remedial action to affect a downgradlent groundwater transect zone. To use the mass flux vs. distance curves, select the condition that best matches your site conditions:
1. Select source type:
• Constant Source. Use for evaluating baseline (no remediation) conditions at sites with relatively constant source concentrations over time
• Decaying Source. Use for evaluating sites where natural attenuation or a remed,ation system is reducing the source concentration quickly at first, then more slowly.
• Step-Function Source. Use for evaluating sites where natural dissolution of the source or a remediation system quickly reduces the source flux by some percentage, and then the reduced source is relatively constant over a long period of time. Examples are a partial excavation of the source, or an intensive remediation effort that removes some fraction of the source quickly, but leaves some fraction behind as a constant source.
2. Select source characteristic. Select source type:
• Constant Source. No characteristic to select.
• Decaying Source. The key factor to consider when selecting a decaying source graph to use is how quickly the source is being decayed. This is represented by the source decay half-life. This guide lets you select a source decay half-life of either 1, 5, or 10 years. For example, if natural attenuation is reducing the MTBE concentration in a source zone by half every 5 years, use the mass flux vs. distance curve for a 5-year source decay half-life. If muLti-phase extraction is reducing the MTBE concentration In a source zone by half every 1 year, use the mass flux vs. distance curve for a 1-year source decay half-life.
