Kazakhstan Sediment Transport and Dredge Evaluation Studies

Gravity has been busy this year working with a Kazakhstan based petroleum company on a port development project in the north Caspian Sea.

Due to the discharges from Ural and Volga Rivers, and the wind-driven sea currents, the north Caspian Sea receives a great volume of depositional material each year. As a result, much of the northern Caspian Sea has a water depth less than 5 meters. Therefore to allow shipping access our client may construct a ~70km channel to a future loading and offloading port facility. Gravity’s extensive experience in dredge management, sediment transport, and sediment toxicology was requested to help create a appropriate plan for a project of this magnitude.

Since the end of July, Gravity has had staff on the ground in Kazakhstan working on a large environmental field effort to collect data for the Environmental, Social, and Health Impact Assessment (ESHIA) program. The ESHIA program is used to asses the multiple impacts a project will have on its surroundings, and weighs quite heavily in the overall decision making process. Gravity is involved in data collection and oversight in three main areas.

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  1. Hydrodynamic and Morphodynamic Model Validation

Engineers have created a set of numerical models to predict current velocities and the corresponding rates of sediment transport and deposition. Gravity is deploying current profiling and turbidity instruments at strategic locations to collect data over an extended time series. Correlating the recorded current velocities with turbidity measurements will provide accurate volumetric rates of sediment transport. This data will be used to calibrate the current models.

2.    Environmental Sediment Cores

Just like any other dredge project, sediments within the project site must be analyzed for potential contaminants. Given the scale of the project, over 180 environmental cores were taken along the proposed channel. Gravity oversaw the offshore drilling, and processed all environmental samples for laboratory analysis.

3.    Biological Survey

The Caspian Sea sustains unique and diverse populations of fish, birds and mammals. One of the more interesting species is the endemic and endangered Caspian Seal, a marine mammal found exclusively in the Caspian Sea. Gravity biologists conducted biological surveys of the proposed channel and surrounding islands for present biological communities. Additional fish surveys are planned for the fall or early spring.

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