PROJECT PROFILE | STATISTICAL CLOSURE
New Statistics Leads to Site Closure
EnviroSolutions, Inc. applied an innovative statistical method to show that a site was clean.
A major corporation redeveloped an industrial site in Detroit, Michigan. Due to PNA concentrations in the soil, the former consultant submitted a restricted closure plan. With time, the corporation found the requirements of the restricted closure to be burdensome.
The corporation’s environmental manager hired EnviroSolutions to investigate the potential for an unrestricted closure. EnviroSolutions researched several different options for closing the site and decided to re-analyze the site data using a statistical approach, called Bootstrapping.
EPA studies have shown conventional statistical methods result in overestimates of contamination levels and that Bootstrapping is a more accurate analysis.
The conventional analysis of the site data showed the upper confidence limit of the PNA concentrations exceeded the cleanup criteria by 10%. The Bootstrap method indicated the PNA upper confidence limit was actually 15% less than the cleanup criteria. Based on these results, the corporation was able to proceed with an unrestricted site closure.