Dredging

About: Dredging is a research topic. Over the lifetime, 3300 publications have been published within this topic receiving 28325 citations.

New Bedford Harbor Superfund Project, Acushnet River Estuary Engineering Feasibility Study of Dredging and Dredged Material Disposal Alternatives. Report 11. Evaluation of Conceptual Dredging and Disposal Alternatives

Abstract: : This report evaluates conceptual dredging and disposal alternatives for the Acushnet River Estuary, a part of the New Bedford Harbor Superfund Site. Dredging for removal of the highly contaminated sediment and subsequent disposal in upland or nearshore confined disposal facilities or disposal in contaminated aquatic disposal facilities are alternative considered in the Engineering Feasibility Study of Dredging and Dredged Material Disposal Alternatives. Sediment testing and sediment transport modeling performed as earlier tasks of the study form the basis for evaluation of the alternatives. The technical feasibility of conceptual design options is based on site availability, capacity, and characteristics and on sediment physical characteristics and dredged material settling behavior as defined by laboratory testing. Contamination releases during dredging and disposal operations are estimated for each disposal option. A preliminary cost estimate for implementation of each option evaluated is also presented. Keywords: Confined disposal facility, Contained aquatic disposal, Metals, Polychlorinated biphenyl.

Sand dredging and environmental efficiency of artisanal fishermen in Lagos state, Nigeria

Abstract: Environmentally detrimental input (water turbidity) and conventional production inputs were considered within the framework of stochastic frontier analysis to estimate technical and environmental efficiencies of fishermen in sand dredging and non-dredging areas. Environmental efficiency was low among fishermen in the sand dredging areas. Educational status and experience in fishing and sand dredging were the factors influencing environmental efficiency in the sand dredging areas. Average quantity of fish caught per labour- hour was higher among fishermen in the non-dredging areas. Fishermen in the fishing community around the dredging areas travelled long distance in order to reduce the negative effect of sand dredging on their fishing activity. The study affirmed large household size among fishermen. The need to regulate the activities of sand dredgers by restricting license for sand dredging to non-fishing communities as well as intensifying family planning campaign in fishing communities to reduce the negative effect of high household size on fishing is imperative for the sustainability of artisanal fishing.

17. Ecological effects of pump-scoop dredging for cockles on the intertidal benthic community

Abstract: Awareness of the ecosystem effects of fishing activities on the marine environment means that there is a vital need to assess the direct and indirect effects of those activities that may have negative effects on target and non-target species. The Edible Cockle Cerastoderma edule is the target of an artisanal and commercial fishery that occurs in estuarine and intertidal habitats across northern Europe. Poole Harbour has opened up its cockle beds to pump-scoop dredging over the last few years. This study investigated the effect of pump-scoop dredging on the intertidal sedimentary environment and the macro-infaunal community. The results demonstrated that the dredging did not have an effect on the size distribution of sediment particles. After the fishery opened, no immediate impact of cockle dredging on the infaunal community was observed. Within 3 months, however, a reduction in species richness and abundance of the benthic community was noted. This may be indicative of a chronic rather than acute impact. However, further investigations are required to assess whether this was directly related to pump-scoop dredging. The findings of this study are discussed in relation to possible impacts on the ecosystem as a whole.

Assessment of the physical impact of a short-term dredging operation on a semi-enclosed environment: South Euboean Gulf, Greece.

Abstract: The potential influence of short-period (May–June 2012) dredging activities (for the installation of a submarine gas pipeline) on physical properties of the marine environment of two shallow-water sites in the Aliveri and Varnavas areas of South Euboean Gulf (Greece) has been evaluated. During the dredging operation in Varnavas, the induced dredge plume traveled up to ~ 750 m from the shoreline, featured by light attenuation coefficient (cp) maxima of 4.01–4.61 m−1 and suspended particulate matter (SPM) concentrations up to 6.01 mg L−1. After dredging the previous parameters reduced to the ambient seawater condition, ~ 0.45 m−1 and < 2.8 mg L−1 on average, respectively. Likewise in Aliveri, the dredging-associated sediment plume drifted offshore up to ~ 400 m from the shoreline, characterized by cp maxima of 2.11–4.86 m−1 and SPM concentrations up to 13.07 mg L−1. After the completion of the excavation and trenching activities, the cp and SPM values were restored to the pre-disturbance condition, ~ 0.6 m−1 and < 2.2 mg L−1 on average, respectively. The migration of the dredge plume in both dredging sites was accomplished through the formation of intermediate and benthic nepheloid layers, whose development and evolution were governed by seawater stratification and flow regime. The dredging-derived SPM levels appeared to increase within a distance of no more than 300 m from the shoreline (near-field zone). Based on data from the literature, this SPM enhancement together with the deposition of a post-dredging residual mud veneer in the near-field zone could deteriorate local marine biota, but in a reversible way.

Evaluation of dredged material proposed for ocean Disposal from Shoal Harbor/Compton Creek Project Area

Abstract: The objective of the Shoal Harbor/Compton Creek Project was to evaluate proposed dredged material from the Shoal harbor/Compton Creek Project Area in Belford and Monmouth, New Jersey to determine its suitability for unconfined ocean disposal at the Mud Dump Site This was one of five waterways that the US Army Corps of Engineers- New York District requested the Battelle Marine Sciences Laboratory (MSL) to sample and evaluate for dredging and disposal in May 1995 The evaluation of proposed dredged material from the Shoal Harbor/Compton Creek Project area consisted of bulk chemical analyses, chemical analyses of dredging site water and elutriate, benthic and water-column acute toxicity tests and bioaccumulation studies Eleven core samples were analyzed or grain size, moisture content, and total organic carbon Other sediments were evaluated for bulk density, specific gravity, metals, chlorinated pesticides, polychlorinated biphenyl (PCB) congers, polynuclear aromatic hydrocarbons, and 1,4- dichlorobenzene Dredging site water and elutriate water were analyzed for metals, pesticides, and PCBs