An environmental and economic assessment of topsoil production from dredge material

This paper investigates the environmental and economic feasibility of producing manufactured topsoil at the Port of Waterford, Ireland from two waste streams; dredge material and household waste. Four dredging and dredge material transport scenarios to a topsoil production facility are proposed; a trailing suction hopper dredger (TSHD) with pipeline transport, a grab hopper dredger (GHD) with barge transport, a small purchased port owned dredger (TSHD) with hopper transport and a leased dredger (GHD) with hopper transport. The stringent legislative framework governing the proposal is outlined. A detailed environmental and economic analysis is presented for each scenario. The environmental analysis presents results for CO2 transport emissions and also presents sensitivity analyses for different projects parameters. The economic analysis presents the annual profits or losses for each scenario for a range of topsoil production quantities and integrated into the current dredging regime at the Port of Waterford. Economic sensitivity analyses are presented for different project parameters. This paper recommends, based on the analysis undertaken, the use of a leased dredger with hopper transport to transport the dredge material to the topsoil production site as the most feasible option currently available at the Port of Waterford. The proposal provides an environmentally sustainable end use for dredge material as an alternative to disposal at sea.