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Assessing and evaluating environmental turbidity limits for dredging


The latest CEDA Information Paper discusses crucial concepts for setting turbidity limits, with a balance between protecting the environment and still allowing for dredging in a cost-effective way. 

In 2016, the CEDA Environment Commission (CEC) conducted a survey, of companies and organisations working with dredging, to investigate which environmental turbidity limits existed for dredging projects, how they were set, and how the environmental limits affected the projects financially and operationally. Interestingly, the survey showed that compliance monitoring contributed about 1–5%, on average, to the cost of the dredging project.

News - Turbidity Limits Paper - Picture 2 - 2020-05-25 // dsc02029.jpg (291 K)Respondents indicated that they understood and supported the need for environmental turbidity limits. However, they didn’t necessarily think that the majority of the limits were scientifically or environmentally based. Limits varied regionally, and by project, but rarely seemed to be linked to local sensitive receptors. Taking into account the generally high costs of compliance monitoring, and the environmental risk that a limit might be set incorrectly, the CEC raised the question: Is there a need for guidelines on how to set realistic and effective environmental turbidity limits for dredging?

The resounding reply was “yes”, so the CEC set up a working group to look at the issues and produce a paper. 

Their work highlights a general approach to set or discuss turbidity limits for dredging applications. Connections to background information, monitoring and management measures (as relevant where exceedance occurs) are provided.

CEDA Information Paper: Assessing and Evaluating Environmental Turbidity Limits for Dredging is now available to download from "Related documents"on the right and from this page.