We recently undertook a performance review for remediation projects across our company, to determine why some projects were technically outperforming others. Projects were judged on how well they met technical, regulatory and client objectives. We hoped to identify key characteristics of successful projects that could be extended to all projects, to more reliably select the most appropriate remedy for a given set of circumstances. One characteristic of successful projects stood out: all of the high-performance projects followed a pattern of interpretation, analysis, review and revision, at all stages of project development and operation. The most successful project teams were highly adaptive and were consistently able to develop and apply technically sound solutions to groundwater restoration problems. Underlying each of the best projects was a good site model that evolved from highly conceptual at the outset, into a more quantitative, predictive form as the project matured. Most importantly, the site models on the most successful projects continued to evolve during remedial system operation.