Superfund soil cleanup: developing the Piazza Road remedial design.

A statistical approach was used to develop the remediation and soil sampling strategy at the Piazza Road dioxin site (an EPA Superfund site in Missouri). The source of the dioxin was contaminated waste oil that was used as a dust suppressant. This site was used as a test case to determine if a "surgical" remedial design could be developed. This new approach was compared to the historical approach taken by U.S. EPA Region 7 in Missouri. A pilot study provided information on the local spatial pattern of dioxin, so that sampling designs could be evaluated and costs of remediation could be estimated for different remedial strategies. Sampling designs were evaluated by a Monte Carlo approach, where the laboratory analytical error and sampling error due to spatial variation of dioxin were modeled based on the results of the pilot study and the historical site data. The optimal cleanup unit size was determined to be 14x14 ft, or 1/24th of the historical cleanup unit size. A companion paper describes the performance achieved and the dollar 5,900,000 cost savings that resulted from applying the improved design. This case study clearly shows the value of environmental data, where the use and quality of the data are established as a part of planning the site remediation.