HPS is an analytical model for simulating three-dimensional contaminant transport from a Horizontal Plane Source in a uniform regional ground water flow field. The model incorporates advective and dispersive (scale-dependent) transport, retardation, and first-order decay. The model supports multiple sources with either continuous or time-varying source releases. Source strength is internally calculated from source concentration, recharge rate, and source area.

A combination of Green's functions are used to derive a solution for the instantaneous release from a plane source in a homogeneous aquifer. A convolution integral is applied to allow calculations for non- instantaneous releases.

The model is well-suited to make screening-level calculations regarding contaminant transport from landfills, waste lagoons, land treatment facilities, and areas of pesticide applications.

The model has a simple, text-based data entry interface with options to save data in a file, or to run a previously prepared data file. Output is echoed on screen and in a text file. Optionally, results can be saved in a x-y-z-C file for graphic postprocessing.

HPS is a public domain MS-DOS based mode. It runs in a DOS window under MS Windows 3.1 and is distributed complete with source code, executable image, and example data sets. The documentation includes installation instructions and a user's manual.

SYSTEM REQUIREMENTS Intel 80i86 processor with math coprocessor, 640 Kb (conventional) RAM, and DOS 3.0 or higher.

Author: D.P. Galya (ERT, Concord, Massachusetts).