Licensed Treatment & Recycling Facility
Treatment and Disposal of Contaminated Dredgings
Contaminated dredgings from a busy fishing harbour had to be disposed of, following the withdrawal of the licence to dispose of these to sea. Contamination consisted mainly of anti-fouling agents Tri-butyl-tin (TBT’s) and hydrocarbons. Total volume of dredging was approximately 11,000 m3. Landfill disposal of the dredgings as they arose from the dredging process was very expensive.
A waste management licence for a treatment facility was obtained from the regulators for the project duration and a water discharge licence granted. A specially designed storage lagoon was constructed for the dredged material, with a sump in one corner to collect the liquid run-off. This liquid run-off was treated by pumping through a series of filters and separators to reduce contaminant concentrations to acceptable levels before being discharged under licence to the sewer. The dredgings were treated on site by a process know as stabilisation, where cement is added to the material and thoroughly mixed using a specially adapted mixing unit. The stabilised materials were then transported to a landfill to be used as landfill cover.
The client was able to maintain the use of the busy fishing harbour during works and comply with new legislation regarding the disposal of dredgings using an economic solution.
By a process of treatment an engineered material was produced, which rather than being landfilled was used to provide much needed landfill cover for the landfill operator.
Massive savings were made by diverting the dredgings from landfill to instead be used as landfill cover.