For managing of potentially contaminated sites in the province of Lower Austria, one specific focus are former small municipal landfill sites. In 1997, a guideline describing the procedure of preliminary risk assessments regarding groundwater, surface water, air and soil was developed by experts at the water management department of the regional government. By 1998, the guideline was decleared compulsory. Reacting on first experiences of implementing this guideline, a scientific follow-up project "Evaluation and Preliminary Assessment of old Landfills" (EVAPASSOLD) was launched by the year 2000. In this project, a comprehensive investigation of 25 old municipal landfills was conducted. Starting from these results, a first simplified investigation approach was developed and tested at 15 additional landfills. Thus, the final evaluation referred to 124 data sets from a total of 40 sites. As a result, practically suitable (i.e. simple and cost-effective) investigation techniques and factors controlling risks at the stage of preliminary assessments have been identified. With regard to redevelopment one essential conclusion is, if during the operation period of a municipal landfill the total precipitation exceeded 25,000 mm, limit values for unpolluted soil and inert waste are met. Furthermore, according to a statistical analysis with regard to parameters characterising degradation processes, in particular TOC, ammonium and landfill gas components like methane and carbon dioxide, a simple indicator for safe redevelopments is suggested by the criterion: Total precipitation during the operation period/depth of deposit > 4.4 [m/m] i.e.: hNB / T. Hence referring to the scope of the study, the boundary conditions in applying this indicator criterion need to be recognised: - municipal solid waste of small villages only; - no hints on hazardous wastes; - total deposition volume < 50,000 m³; - average depostion depth < 5 m.