Hydrocarbon Spill Screening Model (HSSM). Volume 1. User's guide. Research report

This user's guide describes the Hydrocarbon Spill Screening Model (HSSM). The model is intended for simulation of subsurface releases of light nonaqueous phase liquids (LNAPLs). The model consists of separate modules for LNAPL flow through the vadose zone, spreading in the capillary fringe, and transport of chemical constituents of the LNAPL in a water table aquifer. These modules are based on simplified conceptualizations of the flow and transport phenomena which were used so that the resulting model would be a practical, though approximate, tool. Both DOS and Windows interfaces are provided to create input data sets, run the model, and graph the results. These interfaces simplify the procedures for running the model so that the model user may focus on analysis of his/her problem of interest. To that end, guidance is given for selecting parameter values and several utility programs are provided to calculate certain parameters. Typical example problems, which begin with a general problem statement, show exactly how each parameter of the model should be chosen.