The report is an interim version of the user's manual for the RADM Scavenging Module (RSM). The scavenging module simulates wet removal and aqueous-phase chemical processes as they occur on a regional scale. It is designed for inclusion into a regional-scale Eulerian code that does not explicitly account for processes involving clouds and precipitation. Using surface precipitation rates and vertical profiles of temperature and moisture for a regional scale grid square, the scavenging module calculates steady-state cloud, precipitation and vertical velocity fields for subgrid areas representing stratiform, convective and fair weather cumulus clouds. It then calculates the effects of aqueous phase chemistry, precipitation scavenging and transport on the pollutant fields presented by the host code for a specified time period (one hour). The version of the RSM described in this report includes the stratiform and convective storm component; it does not include the fair weather cumulus (although provisions for including this component are outlined). A description of several proposed benchmark tests is provided; the results of these tests will be published in future reports.