Natural Attenuation of VOCs at Wisconsin Landfills: A Preliminary Evaluation

Introduction: This study investigates whether the processes of natural attenuation of volatile organic compounds (VOCs) that function in groundwater at small-scale sites such as spills and leaking underground storage tanks also apply at large-scale municipal solid waste (MSW) landfills. Any one of the following processes can attenuate VOCs: volatilization, sorption, dispersion, dilution, or degradation. At small-scale sites, a natural attenuation process that has been shown effective is that of biodegradation which results in loss of contaminant mass and a reduction in plume size. This investigation evaluated various VOC trends at 31 old, closed landfills throughout Wisconsin in an attempt to answer the following questions:

1. How do VOC concentrations change over time?
2. Does natural attenuation seem to be taking place?
3. What are the principal natural attenuation process/es influencing VOC concentrations at Wisconsin landfills?
4. What role do site characteristics play regarding natural attenuation?
5. What considerations need to be made to assess whether natural attenuation is a valid remedial option?