Analysis of Water Shock Data and Bubble Screen Effectiveness on the Blast Effect Mitigation Test Series, Wilmington Harbor, North Carolina

The U.S. Army Corps of Engineers, Wilmington District (CESAW), has been tasked with deepening the existing shipping channel for the Port of Wilmington, NC. Because well cemented rock will be encountered, in places, in the deepening or widening of Wilmington harbor, blasting will be required to fracture rock for removal. Experience has shown that the water shock produced by underwater blasting operations can produce significant fish kills and pose a threat to other aquatic life. Several endangered species inhabit the Cape Fear River in and near the shipping channel. Because of this, minimizing the biological effects of the blasting is of great interest. Several water shock parameters have been associated, to varying degrees, with damage to aquatic life forms. Munday, et al (1986) provides an excellent overview of prior studies in this area. Peak water shock pressure is the parameter most commonly related to fish injury. However, Yelverton (1975) cites peak impulse as the most reliable parameter for predicting lethal ranges from underwater explosions. Peak energy flux density and the rate of pressure change have also been used as lethality predictors.