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C.E. Aziz C. J. Newell A.P. Smith Groundwater Services, Inc. . BIOCHLOR A Screening Level Natural Attenuation Model and Database for Solvents. J.R. Gonzales P.E. Haas Air Force Center for Environmental Excellence. Y. Sun T.P. Clement Battelle Pacific Northwest National Laboratory.
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C.E. AzizC. J. NewellA.P. Smith Groundwater Services, Inc. BIOCHLOR A Screening Level Natural Attenuation Model and Database for Solvents J.R. GonzalesP.E. Haas Air Force Center for Environmental Excellence Y. Sun T.P. Clement Battelle Pacific Northwest National Laboratory
BIOCHLORModel Domenico Solution for Groundwater Transport Reductive Dechlorination/ Sequential First Order Rxns
Why Use BIOCHLOR? Method for Estimating Plume Lengths • System to Organize Site Data • Tool to Help Understand Site Processes • Screening Tool for Applicability of NA • Supporting Line of Evidence for NA
BIOSCREEN vs. BIOCHLOR: Similarities nDomenico Analytical Model n Microsoft Excel Platform n User-Friendly Interface n Based on Site Database nFree Over the Internet
BIOSCREEN vs. BIOCHLOR: Differences BIOSCREEN BIOCHLOR nPetroleum Hydrocarbon Sites – BTEX n Biodegradation: nSolvent Sites nMore Complex Biodegradation: - 1st Order Decay or - Electron Acceptor Limited - Sequential Reactions - Different Zones
BIOCHLOR: Key Processes n Advection (1-D) nDispersion (3-D) nSorption n Biodegradation: - Reductive dechlorination - Sequential reactions (parents to daughters) - Limited hydrolysis nDifferent biodegradation zones
BIOCHLOR Model Domenico Solution for Groundwater Transport Reductive Dechlorination/ Sequential First Order Rxns
Sequential Reactions l2 l3 l4 l1 PCE TCE DCE VC ETH Rate PCE = – l 1 C PCE Rate TCE = l 1 y 1 C PCE – l 2 C TCE
Reactive Transport Equations d CPCE = L ( CPCE ) - l 1 CPCE Rate PCE = d t d CTCE = L ( CPCE ) + l 1 y 1 CPCE - l 2 CTCE Rate TCE = d t d CTCE = L ( CPCE ) + l 2 y 2 CTCE - l 3 CDCE Rate TCE = d t etc. ... A-D Equation(1-D advection, 3-D dispersion) d C1 d 2C1 d 2C1 d 2C1 + Dz + Dy + Dx L ( C 1 ) = – v d x d z 2 d y 2 d x 2
BIOCHLOR Model Domenico Solution for Groundwater Transport Y. Sun / T.P. Clement Transformation
Results in BIOCHLOR 1.0 TCE 0.8 0.6 DCE 0.4 0.2 VC 0 Distance from Source
Source PCE TCE DCE VC ETH PCE TCE DCE VC ETH Zone 1: High Decay Rates (Carbon Present) Zone 2: Low Decay Rates (No Carbon) BIOCHLOR Model: Other Features Two Reaction Zones for Mixed Sites Zone 1 Zone 2
BIOCHLOR Model: Other Features n Superimposed Sources (Connor et al., 1995) nSingle Vertical Plane Source Source 1 Source 2 Source 3
BIOCHLOR Model: Summary n Predicts Parent, Daughter Compound Concentrations n Provides Analytical Solution to Transport Equations with Sequential Reactions n Simulates Two Biodegradation Zonesfor Mixed Sites Zone 1 Zone 2
BIOCHLOR Version 2.0 nRate Constant Decision Support System n Source Decay Option n Animation Feature
How To Get BIOCHLOR . . . Version 1.0: n Available on CD OR n Download free Currently: www.gsi-net.com Jan. 2000: www.epa.gov/ada/models.html ( CsMOS Web Page ) Version 2.0: n Available: Fall 2000
BIOCHLOR Demonstration Case Study: Cape Canaveral AS, Fire Training Area Release: Solvents, degreasers, JP fuels (1965-1985) Site Hydrogeology: n Avg. Depth to Groundwater 5 ft BGS 1.8 x 10-2 cm/sec nHydraulic Conductivity 0.0012 ft/ft nHydraulic Gradient nTypical Groundwater Seepage Velocity 112 ft/yr