Historical costs are usually found in existing documentation. However, it is sometimes very difficult to determine whether a past cost is relevant to the issue at hand, or whether the cost information is incomplete. In such situations, detailed knowledge of engineering costs and practices proves extremely useful to making correct, defensible calculations. Mr. Ammann has examined past cost information related to many Superfund sites and has helped to assemble appropriate documentation, including realistic engineering cost estimates to fill gaps in available information.
Estimation of future costs poses unique challenges, as the amount of information may vary over a wide range, depending on many different variables that are not yet known with certainty. Engineering and economic techniques are useful in projecting investment and annual operating and maintenance costs for many years in the future. However, multiple issues may affect future costs, including changes in the speed and direction of migrating plumes of contaminants; possible alterations in future regulatory requirements; unanticipated failure of control measures; and development of new technologies, which may or may not work as anticipated. Mr. Ammann has helped to quantify these uncertainties so they can be factored into probabilistic estimates of future cleanup costs.