"This document describes how to use the Industrial Waste Management Evaluation Model (IWEM). IWEM is the ground-water modeling component of the Guide for Industrial Waste Management (Guide) (U.S. EPA, 2002d), which has been developed by the U.S. Environmental Protection Agency's (EPA's) Office of Solid Waste (OSW) for the management of non-hazardous industrial wastes. A companion document, the Industrial Waste Management Evaluation Model Technical Background Document (U.S. EPA, 2002c), provides technical background information. It is strongly recommended that you take the time to understand the technical background of IWEM in order to make the best use of this program. This section of the User's Guide provides an overview of IWEM and its purpose, operation, and application; describes the major components of the system; and provides an overview of how the remainder of the document is organized. "--Introduction.