Field Evaluation of Hopper Dredge Overflow for the Delaware River: Fid-Bau Portal

Field Evaluation of Hopper Dredge Overflow for the Delaware River

J. L. Miller / M. R. Palemo / T. W. Groff

Hopper dredges are often loaded past the point of overflow for economic reasons. As the hopper is filled, dredged material is stored in the hopper until overflow begins. The density of the hopper contents is increased by allowing the low-density supernatant to overflow back into the waterway. As the low-density supernatant overflows, the average density of the hopper contents increases. Thus, more material can be transported per trip to the disposal site or facility resulting in an economical loading. There is normally a tradeoff between the potential economic benefits and potential environmental effects. Overflow results in increased water column turbidity, and supernatant solids may be redeposited near the dredge site. Also, if sediments are contaminated, the overflow may result in some release of contaminants to the water column. Therefore, the relationship between dredge production, density of the hopper load, and the rate of material overflow are important variables in maximizing the efficiency of the dredging operation while minimizing harmful contaminant release.