Beneficial Uses of Dredged Material from the Quonset Point/Davisville Intermodal Port

Abstract

Over the past few years the University of Rhode Island (URI), Marine Geomechanics Laboratory and the Maguire Group Inc. (MGI) have gathered significant data and conducted tests relative to the beneficial use of dredge materials from the Quonset Point/Davisville port in Rhode Island. The objective was to determine possible beneficial use options for the various sediment types that will be encountered. The sources of data consist of earlier subsurface investigations, conducted by MGI, and a joint URI/MGI research project sponsored by the URI Transportation Center in 2000 and 2001. In the recent research project, cores were obtained using a Large-diameter Gravity Corer and a vibracorer. Sediments were characterized using a Multi-Sensor Core Logger for bulk density profiles and then classified in a laboratory/testing program that included Atterberg Limits, grain-size analyses, and organic and chemical testing. The sediments consisted of organic and inorganic silts and silty fine to medium sands. Based on the sediment types, bench scale tests were conducted to determine possible beneficial use alternatives. These alternatives included: direct use for landfill and construction applications, brownfield encapsulation with the low permeability sediments, cement enhancement, lime stabilization, and blending with coarser materials such as crushed demolition debris for use as common borrow. Bench-scale testing included compaction tests, strength tests with the additives, permeability experiments and chemical analyses. The results of unconfined compression strength testing for the cement-enhanced samples achieved strengths commensurate with potential construction materials and flowable fill. Lime stabilization with lime contents ranging from 3% to 7% by weight effectively increased the strength of the inorganic silts. Blending of the fine silty sands with construction debris for use as common borrow fill did not result in practical beneficial use opportunities. Permeability test results indicated that the inorganic silts can be used as a low permeability liner or cover for landfills and for brownfield remediation. For each of these options, however, more research is needed in terms of their economic viability and the effects of salt and dewatering on the measured properties. The results of this research were oriented toward proposed dredging activities at the Quonset/Davisville Port Facilities, but the methodology is applicable to other similar locations.