A possible approach for Tier 2 risk assessments of polluted sites: Framework, computer spreadsheet and application

Owing to the increasing attention placed on problems concerning site pollution that environmental geotechnics deals with, an implementation of Tier2 risk assessment (forward and backward mode) is proposed and developed in a computer spreadsheet. Consistently with a Tier 2 approach, contaminant migration is described by analytical solutions of transport models using site-specific parameters. The calculations are implemented with Microsoft Excel® while the user interfaces, which manage the various worksheets, were built with Visual Basic®. The spreadsheet was validated by comparing it with other available software that implement the same model for a given migration pathway. In the present version, the computer tool is consistent with Italian guidelines for Tiers 2 risk assessment. However, the tool can be easily adapted to comply with different regulations and recommendations. Some illustrative examples of applications are given in the paper: a case study of risk assessment for contaminated site is illustrated and a sensitivity analyses of transport factors to site-specific parameters is presented.