Date of Award

2016

Document Type

Master Thesis

Degree Name

Master of Engineering (Research)

Department

Civil, Structural & Environmental Engineering

First Advisor

Dr. Joseph Harrington

Abstract

Dredging is essential for ports and harbours to maintain navigational access. In Ireland approximately 1.2 million m^ is dredged annually and the management of this dredged sediment is an ongoing issue. This thesis investigates the management options available for marine dredged sediment and examines the technical, environmental and economic feasibility and social acceptability of a range of specific beneficial uses of marine sediment.

A literature review is presented on the international dredging industry and outlines why dredging is an essential infrastructural activity. Current dredged marine sediment management techniques are presented and discussed.

An overview of the Irish dredging industry is developed based on surveys and structured interviews which were undertaken with industry stakeholders. The survey results (based on 46 projects) have quantified the current volumes of dredged sediment generated in Ireland with specific project data gathered including sediment characteristics, sediment volumes generated and sediment management practices. The results show that Disposal at Sea has been implemented for over 85% of sediment generated by volume for the projects surveyed. The results are presented in an updated ‘Dredging in Ireland’ database which was originally developed in Cork Institute of Technology in 2003 and last updated in 2007. Structured stakeholder interviews have provided an understanding of attitudes towards different sediment management practices and the challenges faced.

Sediment samples were gathered and tested from five locations (across four countries) and tested for physical, geotechnical and chemical characteristics. The sediment quality results were analysed and compared to Irish, French, Flemish and Dutch National standards for disposal at sea and different beneficial use standards to allow identification of potential management options. The results show some sediment contaminant values exceeding the national standard limits with the Irish sediment contaminant levels below the upper contaminant limit indicating the potential for beneficial use. The results of the physical, geotechnical and chemical testing have been presented in a Microsoft Excel VBA database.

The site specific data gathered was applied to undertake a technical, environmental and economic analysis identifying the feasibility of different sediment management options. Two scenarios were examined and analysed in detail:

• Land Reclamation in Bantry Inner Harbour, Co. Cork, Ireland

• Environmental Enhancement in Cork Harbour, Co. Cork, Ireland

The analysis of these scenarios highlights the feasibility of developing innovative beneficial uses which will contribute to educating stakeholders on the potential availability of beneficial use options for marine dredged sediment.

Access Level

info:eu-repo/semantics/openAccess

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