Reliability-Based Uncertainty Analysis of Groundwater Contaminant Transport and Remediation June 1999

Mention of trade names or commercial products does not constitute endorsement or recommendation for use. All research projects making conclusions or recommendations based on environmentally related measurements and funded by the Environmental Protection Agency are required to participate in the Agency Quality Assurance Program. This project was conducted under an approved Quality Assurance Project Plan. The procedures specified in this plan were used without exception. Information on the plan and documentation of the quality assurance activities and results are available from the Principal Investigator. iii Foreword The U.S. Environmental Protection Agency is charged by Congress to protect the Nation's land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to a compatible balance between human activities and the ability of natural systems to support and nurture life. To meet these mandates, EPA's research program is providing data and technical support for solving environmental problems of today and building a science knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental risks in the future. The National Risk Management Research Laboratory is the Agency's center for investigation of technological and management approaches for reducing risks from threats to human health and the environment. The focus of the laboratory's research program is on methods for the prevention and control of pollution to air, land, water, and subsurface resources; protection of water quality in public water systems; remediation of contaminated sites and ground water; and prevention and control of indoor air pollution. The goal of this research effort is to catalyze development and implementation of innovative, cost-effective environmental technologies; develop scientific and engineering information needed by EPA to support regulatory and policy decisions; and provide technical support and information transfer to ensure effective implementation of environmental regulations and strategies. This report presents a discussion of the application of the first-and second-order reliability methods (FORM and SORM, respectively) to groundwater transport and remediation, and to public health risk assessment. Using FORM and SORM allows the formal incorporation of parameter uncertainty in the analysis of such applications. The report shows the advantages of the reliability methods over currently available simulation methods, such as the Monte Carlo Simulation method. Special attention is also given to the stochastic sensitivity results obtained as an integral part from the reliability analysis. Numerous examples and case studies are given …