Dredging - How can we manage it to minimize impacts

Sediment plumes generated by dredging can impact sensitive receptors at significant distances from the work area. Potential impacts would normally be identified and quantified through the Environmental Impact Assessment (EIA) prior to project implementation; that may also include a degree of project optimization to reduce impacts. However, there are significant uncertainties in predicting the potential impacts at the EIA stage; key components of the dredging programme such as the dredge methodology, dredge schedule, sediment spill sources and climatic conditions encountered during dredging may not be well defined, and this will typically be reflected in the accuracy of the predictions and potentially also in the choice of mitigation measures. Proactive and informed management of the dredging programme as it is executed can often significantly reduce the risk of or minimise the negative impacts. By better understanding which components of a given programme are critical in terms of potential impacts, the programme can be optimised to minimise the risks. Through modelling and monitoring during execution, impacts may be predicted before being realized, and the dredging programme may be optimized to achieve the environmental objectives while maintaining desired production rates. An example is presented describing a combination of monitoring, both of the dredge plume and at receptor sites, and dredge plume modeling to guide the dredging works