Comparative Risk Analysis for Reconstruction of a Partially Failed Dike System

A sudden and catastrophic failure occurred at a newly constructed dike facility, designated Dikes 19 and 20, along the east side of the Dead Sea shoreline in the Middle East. The failure occurred at approximately 4:30 p.m. on March 22, 2000, resulting in the release of approximately 55 million cubic meters (approximately 72 million cubic yards) of brine and the washing out into the Dead Sea of a 2.6 km (1.6 mi) section of Dike 19. After the engineering assessment of the failure was completed, the owner decided to move forward with a reconstruction plan, reinstating the failed section and rehabilitating the section that did not fail. Accordingly, three viable conceptual reconstruction alternatives were developed for further evaluation. A judgmental risk-based analysis was performed to evaluate the proposed alternatives. Subsequently, a decision tree analysis was performed to assist the owner in making the final decision for the alternative with the lowest risk and reasonable cost. The purpose of the risk analysis was only to determine which reconstruction method would have the lowest comparative risk level. The risk analysis was not intended to simulate the actual cause of failure. This article discusses the decision-making approach based on a fault tree analysis and the comparative risk of failure estimated for the three reconstruction alternatives designated as Alternatives I, II-A, and II-B. The overall risk of failure for each alternative was quantified and compared. Alternative II-B was found to have the lowest risk indicator. In addition, on the basis of risk indicators and construction cost, a decision tree was developed, and Alternative II-B was found to offer the most favorable option for the reconstruction of the failed portion of the dike.