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North Coast Maintenance Dredging Environmental Assessments

Hydrosphere Consulting was engaged by NSW Crown Lands to undertake geotechnical investigations and prepare environmental impact assessments and approvals for proposed dredging operations in several North Coast rivers including Tweed River, Terranora Inlet, Brunswick River and Evans River.  


The geotechnical investigations involved the development of a sampling plan, sediment sampling of proposed dredge material, sample analysis and reporting (including waste classification). Sediment coring was undertaken by vibracoring with a custom core receiver which allowed us to retrieve cores up to 2.0 m in length in water depths to 4 m. The use of our coring methodology and Civil 3D software allowed the identification and characterisation of different sediment types (e.g. silt layers) within the dredge areas and depths of key strata. This information was critical to the project development, environmental assessment and formulation of environmental mitigation measures for the projects.


The environmental impact assessments considered a diverse range of potential impacts associated with the dredging including impacts on seagrass, marine fauna, benthic fauna, shorebirds, water quality and social impacts including  amenity, noise and traffic issues. A range of suitable mitigation measures were developed to minimise environmental risks associated with the works. 

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