Applied Research Center Florida International University Remediation and

Applied Research Center Florida International University Remediation and Treatment Technology Development and Support “Modeling Mercury Distribution in the Watersheds of the Oak Ridge Reservation” MIKE SHE and MIKE 11

Water & Environmental Resources Group Rajiv Srivastava, Ph. D – Associate Director Georgio Tachiev, Ph. D – Project Manager Angelique Lawrence, MS, GISP – Research Analyst Prabhakar Pant, MS, PWS – Research Scientist Weihua Zhang, Ph. D – Research Scientist Yelena Katsenovich, Ph. D – Research Scientist

Background n FIU-ARC is providing technical assistance and performing research on mercury remediation at the Oak Ridge site through: n TASK I: Modeling of mercury speciation and distribution under buildings at Oak Ridge in the soil and groundwater. n n Provide new insight to the potential risks of mercury contamination during D &D operations and thus develop strategies to minimize it. TASK II: Identification and characterization of point and non-point sources of mercury in the LEFPC watershed to derive a conceptual model for the site with regard to mercury mass balance. n Re-establishing framework for Hg TMDL criteria currently established by EPA.

MIKE SHE & MIKE 11 n MIKE SHE - Numerical Integrated Hydrology Modeling n n Covers the entire land phase of the hydrological cycle Not just a 3 -D numerical groundwater model - Includes numerical models for n n n n overland flow unsaturated flow solute transport agricultural practice evapotranspiration By default coupled to MIKE 11 Ideal for distributed rainfall-runoff modeling MIKE 11 - River and Channel Hydraulics n n Versatile one-dimensional hydrodynamic software package Includes process modules for n n n advection-dispersion water quality and ecology sediment transport rainfall-runoff flood forecasting

MIKE SHE Integrated Surface Water and Ground Water Model n Dynamic, user-friendly modeling tool n n n Integrated modeling environment n n n Links regional and local scale models Can be linked to ESRI's Arc. View for advanced GIS applications Includes advanced tools for n n Can simulate entire land phase of hydrologic cycle Is applicable on spatial scales ranging from single soil profiles (for infiltration studies) to regional watershed studies Manipulating time varying data Model calibration Water and mass balance analysis Proven track record in hundreds of consultancy and research applications worldwide

MIKE SHE Hydrologic Processes simulated by MIKE SHE 1 -dimensional unsaturated flow model 3 -dimensional saturated flow groundwater model (rectangular grid) Exchange across boundaries

MIKE 11 Dynamic modeling of river, channel and reservoir hydraulics Industry standard for simulating Flow and water level Water quality and sediment transport in rivers, flood plains, irrigation canals, reservoirs and other inland water bodies Transport and spreading of conservative pollutants and constituents with linear decay (including heat). Dynamic integration with other DHI software allows integration of river & floodplain models with models for watershed processes, detailed floodplain representation, sewer systems & coastal processes Links to external groundwater models and is Open. MI compliant Significant components for FIU-ARC work: GIS Extension - Powerful extension for Arc. MAP providing features for Catchment/river delineation Cross-section and DEM data Pollution load estimates Flood visualization/animation as 2 D maps Results presentation/analysis using Temporal Analyst Stream Flow Characteristics and Solute Transport modules. Includes Unit hydrograph method A lumped conceptual continuous hydrological model A monthly soil moisture accounting model Reference: Graham, D. N. and M. B. Butts (2005) “Flexible, integrated watershed modelling with MIKE SHE. ” Watershed Models, Eds. V. P. Singh & D. K. Frevert Pages 245 -272, CRC Press. ISBN: 0849336090.

MIKE 11 Modeling of non-point pollution

Thank you Questions?

Thank you Questions? ?

An integrated model showing the groundwater table as function of time for a period of 10 years. The following specifications are included: • -evapotranspiration • -precipitation • -saturated groundwater flow • -unsaturated groundwater flow • -river flow • -exchange between: • River and groundwater • Saturated and usaturated zone

COMSOL Multiphysics Earth Science Module n Simulates physics involved in fluid flow, heat transfer, and solute transport n Includes modeling interfaces for n n n Heat Transfer Richards equation Darcy’s Law Solute transport in saturated and variably saturated media Also offers n Unlimited multiphysics couplings - Ties seamlessly into COMSOL Multiphysics and other auxiliary modules to truly model coupled phenomena in the earth. These include poroelasticity, electromagnetic fields, acoustic and structural behavior, and chemical reactions. n Equation-based modeling - All material properties, source terms, and boundary settings can be represented by any arbitrary function of pressure, temperature, concentrations, stress, or any other variable or parameter: In particular, full two-phase flow in porous media can be simulated in this way. n Accessing data - The module features unsurpassed ease with which users can work with fieldgathered data and then couple these to descriptions of material properties.

COMSOL Multiphysics 2 -Phase Flow in Porous Media n n n Flow of air and water within the domain. Uses Richard’s equation to describe n Flow in Saturated zone n Flow in Unsaturated zone n Gas flow Transport of mercury in variably saturated media and in the gas phase. Takes into account exchange with infinite layer above the domain by diffusion and convection (wind effects) Incorporates physicochemical behavior of Hg in soil, water, air phases • Adsorption • Bio- and chemical transformation

Visual MINTEQ n This model is used for calculating the equilibrium mass distribution among dissolved species, adsorbed species, and multiple solid phases under a variety of conditions including a gas phase with constant partial pressures. n Used to calculate equilibrium composition of aqueous solutions in ORR groundwater contaminated with 0. 2µg/L of mercury. n Field and laboratory analytical data used in the model were acquired from the OREIS database.

Visual MINTEQ n Mercury binding to humic substances is an important process in ground and surface waters. n Visual MINTEQ permits use of three (3) different models for computing the complexation of mercury by dissolved organic matter (DOM). n Gaussian n n Does not seem to compute mercury bound to DOM and results with DOM input were not differing from the inorganic mercury compounds distribution without DOM. NICA-Donnan Model & Stockholm Humic Model (SHM) n Results from these suggest that mercury is in the dissolved phase and almost 99. 89% bound to DOM with concentrations starting as low as 0. 5 ppm. n NICA-Donnan model is available only for aqueous mercury speciation and provides comparison between site-specific fulvic acid (FA), which are type 1 (carboxylic - FA 1) and type 2 (phenolic and other - FA 2). n Preliminary modeling results indicate that the percentage of mercury bound to FA 1 and FA 2 depends on groundwater ORP conditions.

GEMS-PSI Gibbs Energy Minimization Selektor (PSI version) for Geochemical Equilibrium Modeling n Broad-purpose geochemical modeling code using an advanced convex programming method of Gibbs Energy Minimization (GEM) implemented in an efficient Interior Points Method (IPM) numerical module. n Can compute equilibrium phase assemblage and speciation in a complex chemical system from its total bulk elemental composition at given temperature and pressure (optionally, with some metastability or kinetic constraints). n Chemical interactions involving (dispersed) solids, solid solutions, gas mixture, aqueous electrolyte (non-)electrostatic surface complexation, and ion exchange can be considered simultaneously in the chemical elemental stoichiometry (+ electrical charge) of the system, i. e. without any additional mass balance constraints for ligands or surface sites.

Progress To Date n Delineation of Lower East Fork Poplar Creek (LEFPC) and White Oak Creek watersheds/subcatchments using Arc. GIS and the Arc. Hydro model. N n Preliminary simulation of overland saturated flow in the White Oak Creek Watershed using MIKE SHE

Progress To Date n Creation of 3 -D mesh for topography of Central Bethel Valley area to examine mercury contamination within ORNL area at a smaller scale as opposed to a watershed perspective. Creation of 3 -D visualizations for Central Bethel Valley mercury contamination. Melton Valley Access Rd Cr ak Bldgs. 4501/4505 e. O el. th Rd e B ey ll Va ee k N Wh it n 2005 GW Hg. Conc. (µg/L) Firs t Cr eek 7500 Bridge

Path Forward A multidisciplinary approach to complex environmental problems • Physico-Chemistry, experimental work • Transport on microscale • GIS and regional modeling • Regulatory compliance

Project Overview Saltcake dissolution studies n Hydraulic properties of saltcake simulants n Oxidative Leaching n Gas Release and Retention n Modeling of flow through saltcake n

Saltcake Dissolution

Saltcake Dissolution Experimental Scale

Saltcake Dissolution Preferential Flow and DIssolution

Saltcake Dissolution Beginning and end of dissolution

Saltcake Dissolution Retrieval Efficiency

Saltcake Dissolution Sodium Retrieval Patterns

Saltcake Dissolution Aluminum Retrieval Patterns

Saltcake Dissolution Nitrite Retrieval Patterns

Saltcake Dissolution Phosphate Retrieval Patterns

Hydraulic Parameters Inverse modeling of effluent rates using van Genuchten’s theory for variably saturated flow

Hydraulic Parameters Hydraulic properties of aging simulant

Hydraulic Parameters I II Variation of hydraulic conductivity III

Hydraulic Parameters Tracer Studies

Numerical Modeling Continuous retrieval and dispersion factors

Numerical Modeling Incremental Drainage and Resaturation

Oxidative Leaching Chromium (III) speciation

Oxidative Leaching Chromium (III) speciation

Oxidative Leaching Pu Predominance Diagram

Oxidative Leaching Pu Predominance Diagram

Gas Release and Retention Experimental Setup

Gas Release and Retention Argon Injection and Release

Gas Release and Retention Argon Injection and Release – Time constants

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