Streamlining Site Characterization Site characterization for municipal landfills can be expedited by focusing field activities on the information needed to sufficiently assess risks posed by the site, and to evaluate practicable remedial actions. Recommendations to help streamline site characterization of media typically affected by landfills are discussed in Section 3 of this report. A summary of the site characterization strategies is presented below. Data gathered during the hydrogeologic investigation are similar to those gathered during investigations at other types of NPL sites. Groundwater contamination at municipal landfill sites may, however, vary in composition from that at other types of sites in that it often contains high levels of organic matter and metals.
Leachate generation is of special concern when characterizing municipal landfill sites.
The main factors contributing to leachate quantity are precipitation and recharge from groundwater and surface water. In many landfills, leachate is perched within the landfill contents, above the water table. Additionally, leachate wells provide good locations for landfill gas sampling. It should be noted, however, that without the proper precautions, placing wells into the landfill contents may create health and safety risks. Also, installation of wells through the landfill base may create conduits through which leachate can migrate to lower geologic strata, and the installation of wells into landfill contents may make it difficult to ensure the reliability of the sampling locations.