Quartz-sand Exploitation from a Dredged Material Disposal Site

Abstract

The purpose of the report is to investigate a dredged-material disposal site for silica sand exploitation. The study area, named "D" deposit, is located south of the Madeleine Islands in the Gulf of St Lawrence. The deposit was cored using a vibro-coring device. The cores were analyzed by mineralogical and chemical methods. Three sedimentary units were found in cores at the dredged-material dumpsite: (a) a buff-colored medium sand composing the cover layer, (b) a massive, grey, coarse sand interpreted as the dredged material, and (c) the underlying natural sediment made of reddish, semi-indurated sand. The sands from the "D" deposit have the chemical and physical characteristics of good, natural-bonded moulding sands. The reserves are estimated at 78,000 m³ (proven) and 150,000 m³ (possible) for the cored area, but the total could be considerably increased if other parts of the present-day dumpsite are considered. The report shows that clean dredged sediment may have a resource value. With increasing environmental constraints along coastlines, the utilization of marine dredged-material in shallow water can help to reduce the exploitation of beaches and nearshore sands and provide, at the same time, a good source of silica-sand.