BIOSCREEN AND BIOCHLOR Natural Attenuation Modeling Tools

1. BIOSCREEN AND BIOCHLORNatural Attenuation Modeling Tools

2. BIOSCREEN • easy-to-use screening model that simulates remediation by natural attenuation (RNA) of dissolved hydrocarbons at petroleum fuel release sites • programmed in the Microsoft Excel spreadsheet • based on the Domenico analytical solute transport model, has the ability to simulate advection, dispersion, adsorption, and biological decay (aerobic and anaerobic)

3. BIOSCREEN Includes three different model types: 1) Solute transport without decay, 2) Solute transport with biodegradation modeled as a first-order decay process (simple, lumped-parameter approach), 3) Solute transport with biodegradation modeled as an "instantaneous" biodegradation reaction (approach used by BIOPLUME models)

4. Intended uses for BIOSCREEN • BIOSCREEN attempts to answer the questions: • How far will a dissolved BTEX plume extend if no engineered controls or source area reduction measures are implemented? • How long will the plume persist until natural attenuation processes cause it to dissipate? • BIOSCREEN is intended to be used in two ways: 1. As a screening-level model to determine if RNA is feasible at a fuel hydrocarbon site. 2. As the primary RNA groundwater model at smaller sites.

5. Limitations of BIOSCREEN • As an analytical model, BIOSCREEN assumes simple ground-water flow conditions. • As a screening tool, BIOSCREEN only approximates more complicated processes that occur in the field.

6. BIOSCREEN input screen

7. BIOCHLOR • easy-to-use screening model that simulates remediation by natural attenuation (RNA) of dissolved solvents at chlorinated solvent release sites • programmed in the Microsoft Excel spreadsheet • based on the Domenico analytical solute transport model, has the ability to simulate 1-D advection, 3-D dispersion, linear adsorption, and biotransformation via reductive dechlorination

8. BIOCHLOR • reductive dechlorination assumed anaerobic • biodegradation follows a sequential first-order decay process • includes three different model types: • solute transport without decay, • solute transport with biotransformation (sequential first-order decay process), • solute transport with biotransformation (sequential first-order decay process with two different reaction zones)

9. Intended uses for BIOCHLOR • BIOCHLOR attempts to answer the question: How far will a dissolved chlorinated solvent plume extend if no engineered controls or source area reduction measures are implemented? • BIOCHLOR is intended to be used in two ways: 1. As a screening-level model to determine if RNA is feasible at a chlorinated solvent site. 2. As an RNA ground-water model to address selected chlorinated solvent problems

10. Limitations of BIOCHLOR • As an analytical model, BIOCHLOR assumes simple ground-water flow conditions. • As a screening tool, BIOCHLOR assumes uniform hydrogeologic and environmental conditions over the entire model area. • BIOCHLOR is primarily designed for simulating the sequential reductive dechlorination of chlorinated ethanes and ethenes.

11. BIOCHLOR input screen