A technical assessment of topsoil production from dredged material

This paper presents an investigation into the technical feasibility of producing manufactured topsoil from dredged material from the Port of Waterford, Ireland. A survey of the local topsoil market was undertaken yielding information on topsoil cost, volume of material used annually and the concerns of the users regarding dredged material. The dredged material was analysed for its physical, chemical and nutrient characteristics. Fourteen different dredge material mixes were developed with two mixes of established topsoil for testing and growth trials. Dewatering and desalination of the mixes was undertaken with continuous monitoring. pH adjustment and organic amelioration, from household organic waste, was analysed. Growth trials were undertaken to compare the growth performance of the dredged material mixes with the established sources available on the marketplace. The optimal mix identified was a 60% coarse, 40% fine mix with organic amelioration to 6% and pH adjustment to 6.75. The treatment process improved both the germination rate and the overall biomass production. The creation of manufactured topsoil from dredge material was found to be technically viable.