Remediation of nonaqueous phase liquid (NAPL)-impacted sites is difficult and costly. Even with enhancements (e.g., thermal, chemical), mass transfer constraints of NAPL dissolution govern control of sources and the attainment of cleanup goals. To better manage expenditures, the Department of Defense (DoD) needs a scientifically-based, process-centric method to evaluate the extent of control provided by past NAPL remediation and the potential benefit of additional treatment. Current approaches to predict the impact of NAPL remediation include (1) screening models, which lack a physical basis and are overly simplistic, and (2) numerical transport models, which are immensely complex and costly. The objective of this project is to establish a practical and cost-effective method to assess source control at NAPL sites by applying a volume-averaged model using site- and technology-specific NAPL dissolution rates.