Central Dredging Association

Understanding dredging

Shedding Light on Turbidity Guidelines

Work is well underway on the latest CEDA information paper on guidelines for assessing and evaluating environmental turbidity limits for dredging. The main aim of the paper is to facilitate knowledge exchange on the topic, along with an assessment of which parameters should be included in the evaluation at a local level both in terms of setting turbidity limits and evaluating turbidity limits.

The CEDA working group tasked with drafting the guidelines have been working diligently on the paper since last summer. They met recently on 7th February, at the Jan De Nul offices in Aalst, Belgium, to discuss progress and take the information paper to the next stage of editing.

The first order of the day was to agree on the definition of the term ‘turbidity’ in this context. After a long discussion, the working group agreed to keep it as it was but to add in the other key parameters including: Suspended Solids Concentration (SSC), Total Suspension Solids (TSS), Nephelometric Turbidity Units (NTU) and Formazin Turbidity Units (FTU).

The rest of the meeting was spent going through the draft document and finalising the format for the outstanding sections. It was also agreed that proper emphasis should be given, in the paper, to the balance between monitoring needs and the environmental gains.

As the meeting progressed it was clear that the working group had done some excellent work and the proposed content was so comprehensive that the finished paper would need a few more pages to do it justice. With that, the working group wrapped up with a sense of a job well done and are already looking forward to their next meeting, in the Netherlands, on 26th of March.