Choosing Alternatives: The Air Force Center for Engineering and the Environment (AFCEE) commissioned the development of a "Decision Tool" to assist in determining the appropriate kind of remedial activity for a landfill. The rules and regulations governing landfill remediation are numerous and complex. The "Decision Tool" greatly simplifies the process in support of developing remedial decisions for landfills based on the available data. Most users will need to use only one or two of the decision charts in the document. Each chart is linked to specific notes and help topics discussed in the document to provide more detailed information, as needed, to facilitate the process. For example, the figure shown below is derived from the decision tool and shows the path to a no further action decision. The figure demonstrates that only a small part of one chart of the "Decision Tool" is needed for that decision.

The First Decision: The AFCEE also commissioned the development of a quick, inexpensive means to make a first assessment regarding the applicability of alternative remediation methods. This preliminary assessment is based on potential evapotranspiration (PET), which is the maximum amount of evaporation plus plant transpiration that is possible at a site. PET is controlled primarily by solar radiation, wind, and air temperature. The actual ET is less than the PET, and may be equal to annual precipitation. Where annual PET is larger than annual precipitation, the ET cover is a viable option for controlling water movement into the waste in a landfill. The AFCEE supported the development of estimates of the PET/precipitation ratio for Air Force bases within the continental United States; the results are available in "Vegetated Landfill Covers and Phytostabilization- the Potential for Evapotranspiration-Based Remediation at Air Force Bases".The figure shown below summarizes the results of that evaluation and illustrates the simplicity of its use. The full report contains results of the estimate for 109 Air Force bases. Also available from AFCEE is the document " Evaluating Evapotranspiration (ET) Landfill Cover Performance Using Hydrologic Models." Published in January 2004, this document discusses cover requirements, design issues, currently available hydrologic models, and provides an assessment of the accuracy and usefulness of engineering models that may be used to evaluate or design ET landfill covers.