Proper understanding of the various dredger types linked to the behavior of dredging spoils can easily be turned into a cost-effective EIA and environmental monitoring and thus lead to huge savings on capital and maintenance costs. This is the lesson learned from amongst others Malaysia and Singapore.

Typical environmental issues associated with dredging spill are:

• Light attenuation is significantly reduced in dredging plume which inevitably will impact light sensitive organisms like corals, sea grass, mangroves etc
• If sedimentation rate is larger than the self cleaning ability of the affected species then mortalities will occur
• Other potential effects are decline in DO levels due to increased sediment oxygen demand as well as potential release of toxic metals from sediment

Inherently the impact depends on the magnitude and duration of exposure. Thus, the accurate prediction of dredging spill is crucial for optimal dredging operations as well as the environmental impact assessments.

Traditional approach over-estimates concentrations close to operation and under-estimates remote concentrations. An alternative method of simulating spill from a trailing suction hopper dredger operation has been developed and proven successful in applications in both Malaysia and Singapore.