General TREECS Features

•     Option of using three different chemical-specific constituent databases.
•     Health Benchmark database is provided.
•     A Hydro-Geo-Chemical Toolkit (HGCT) is included for estimating input parameters.
•     A GIS tool is provided for using spatial data to characterize site conditions.

TREECS Tier 1 Features

    Basic Model Assumptions

•     Area of Interest (AOI) is homogeneous, well mixed, with uniform properties and MC concentrations.
•     Impact areas are the main focus of an AOI assessment; the capability to address firing points more fully can be added later.
•     The MC residue mass loading into the AOI is constant or steady-state based on average annual munitions use.
•     No mass loss from the system, such as decay/degradation or volatilization, is assumed.
•     Solid phase MC mass resulting from loading is assumed to be instantly available as aqueous phase (dissolved and adsorbed to soil particles), i.e., dissolution is not included.
•     Reversible, equilibrium partitioning is assumed for distribution of MC mass between dissolved and adsorbed to soil.
•     Average annual hydrologic parameters are used to drive the fate/transport models.

    Model Features

•     Steady-state MC mass loading is based on average annual munitions use.
•     Steady-state soil model with an analytical solution is used.
•     The RECOVERY model is used for receiving surface water and sediment assessment; the model assumes a 0-dimensional, fully mixed water column and 1-dimensional (1-D) vertical sediment layers.
•     The MEPAS aquifer model is used for receiving groundwater assessment; the model assumes 1-D horizontal advection with 3-D dispersion.
•     Tabular comparisons of receiving media projected concentrations for comparison to protective health benchmarks are available.

TREECS Tier 2 Features

    Basic Model Assumptions

•     Loadings, models, and results are time-varying (i.e. not at steady-state).
•     MC loadings are based on annual munitions use and can vary year to year.
•     AOI soil is homogeneous as with Tier 1.
•     Impact areas are the main focus of an AOI assessment; the capability to address firing points more fully can be added later.
•     System losses for degradation and volatilization are included.
•     Both solid phase and non-solid phase (dissolved, adsorbed, and vapor) mass balances are performed with dissolution from the solid to the non-solid phase.
•     Reversible, equilibrium partitioning is assumed for distribution of the dissolved, adsorbed-to-soil, and vapor MC masses within the non-solid phase.
•     Additional media and pathways are included, such as vadose zone below the soil horizon and transfers from groundwater to surface water.
•     Average annual hydrologic parameters are used to drive the fate/transport models.

    Model Features

•     Users will be required to input more information but will also have far more flexibility in modeling applications; results should be more definitive than for Tier 1.
•     MC mass loadings are based on annual munitions use.
•     A time-varying soil model is included with a numerical solution.
•     MEPAS Vadose Zone model is included; the model assumes 1-D vertical transport.
•     MEPAS Aquifer model is included as described for Tier 1.
•     RECOVERY surface water model is included as described for Tier 1.
•     Contaminant Model for Streams (CMS) is also included for surface water and sediments; the model assumes 1-D longitudinal (stream-wise) transport.
•     Input sensitivity and uncertainty can be performed using Monte Carlo simulation with Latin Hypercube sampling to provide output confidence limits.
•     Graphical viewers are included for examining time-varying results along with uncertainty confidence limits and protective health benchmarks.