Floating Spatial Domain Averaging in Surface Soil Remediation

Cleanup plans for contaminated surface soil are frequently developed with the goal of ensuring that regulatory criteria for risk exposure are met after remediation. Currently, some of the plans for Superfund sites are based on the premise that a concentration equal to the average goal or based on a confidence level expression of the concentration measurements is not to be exceeded (NTE). However, in cases of widespread low-level contamination, the NTE constraint may result in lowering risk well below the regulatory criteria and substantially increasing remediation costs. Alternative methods based on spatial averaging are developed and explored in this paper. Floating spatial domain averaging (FSDA) is a multi-criteria decision-making tool in which concentrations or risk factors are averaged over domains that represent exposure areas. The domains are variable in space. The averaging domain floats over the surface in increments representative of the sample or cells spatially interpolated raster units. This allows for the incorporation of domain-wide topological information into the averaging operation around each cell. Floating domain averaging can be done manually or with the aid of geographical information systems (GIS). Additional marginal cost or cleanup objectives can be incorporated into the model and linear programming solutions used as a multi-objective decision-making tool.