These solvents have created significant groundwater contamination at many federal facilities. Since 1976, when RCRA was established, the use and disposal of these solvents have been carefully regulated and many chlorinated solvents have been replaced with less harmful substitutes. Natural attenuation may be effective in achieving cleanup goals at some sites, particularly when these goals are based on site specific risk reduction. For example, if contaminant migration is limited to shallow groundwater, and groundwater use can be controlled, natural attenuation may eventually achieve cleanup goals on some sites. However, natural attenuation is more likely to play a role in cleaning up a portion of a chlorinated site.
Natural attenuation is more likely to clean up areas that have lower levels of contamination.
Such areas are normally found outside of highly contaminated source areas, or at sites with relatively small source areas. Less generation or transfer of wastes. Less intrusive and disruptive than engineered methods. Can be combined with active remedial measures or used to remediate a portion of the site. Remediation costs may be lower than with active remediation.