Evaluating environmental turbidity limits

The International Association of Dredging Companies’ (IADC) latest edition of their Terra et Aqua magazine featured a very interesting article named ‘Assessing and evaluating environmental turbidity limits for dredging’.

The maintenance and development of ports, harbors and waterways requires dredging, a process which relocates large volumes of sediment. A method to set limits on the release of suspended sediments into the water column is set forth.

Mitigating the impacts of turbidity is usually managed by limiting the amount of suspended sediments released at the dredging sites or entering sensitive areas.

For dredging projects around the world, many different limit definitions and corresponding turbidity monitoring methods have been applied. However, the basis or background of these definitions is not always clear.

Sometimes a very strict or alternatively very ambiguous definition of the turbidity limits can have a serious impact on the project execution methodology proposed by bidding contractors and thus on their quoted price. A very loose definition of the turbidity limits can additionally have a huge impact on the local environment.

In many cases, turbidity limits may even appear to be defined without consideration of the specific sensitive receptors that are supposed to be protected.

One potential risk that may result is that on the one hand, the turbidity limits may be overly conservative, while on the other hand, they may also be inadequate in protecting the sensitive receptors.

Author: Klavs Bundgaard (NIRAS)

Read the new article: ‘Assessing and evaluating environmental turbidity limits for dredging’: https://bit.ly/Terra-Turbidity

Photo: IADC