Characterization of zebra mussel transport near a pump intake

The appearance and explosive population growth of zebra mussels have impacted many facilities near water, such as electricity-generating power plants. These mussels can congregate at plant-water-intake structures where proactive maintenance actions, such as mussel kills, must be performed. However, once dead, the mussel debris is a potential contaminant drawn into the plant via cooling water pump suctions; this may affect piping and components downstream of the pump suctions. Thus, it becomes necessary to establish whether sufficient water velocity, from the suction action of a pump, exists to entrain shell debris. Although entrainment data for zebra mussel shells and shell fragments are lacking, this study employs a generalized empirical method based on other types of bivalve shells. Basic pump-suction considerations yield an entrainment volumetric zone in which any shells would be drawn into the pump. A calculated sample zone extends slightly less than one meter from the centerline of the pump-suction pipe and is cylindricalin shape. This approach can be generalized to various pump intake configurations and bivalves, providing a predictive means for evaluating plant system contaminants. Experimental data, although outside the scope of this study, may be used to refinethe modeling.