Surveys for Dredging and Bed Levelling

PHS have extensive experience in conducting surveys in support of dredging and bed levelling campaigns. Our name is a testament to our precise data collection and analysis. We have experience conducting survey operations throughout an entire dredging project. This includes pre dredge surveys to progress surveys and final post dredge surveys. We work with our clients to plan for a strategically targeted dredging campaign ultimately saving costs and improving productivity.

Results of dredging and bed levelling

To maximise the use and productivity of our ports it is essential that we have a clear and concise understanding of factors that affect the available depth. The post-dredge survey is the only activity that shows the results of a dredging campaign to enable assessment of the available depth. The survey must be accurate with uncertainty kept to a minimum to enable a precise calculation of under keel clearance. The survey results must also be of a high enough resolution to capture any areas or objects that may pose a danger to navigational safety.

The results of the dredging campaign are used by the port operators, mariners, and other stakeholders to plan shipping schedules and allowable drafts for vessel entering or leaving the port.

The PHS dredging survey process

We focus on the accurate reporting of the maintained depth of navigation channels, berths and anchorages. Accurate and reliable pre, progress and post-dredge hydrographic surveys are important processes of a dredging campaign. These enable a strategic and targeted dredging operation that considers the requirement of navigational safety and Under Keel Clearance (UKC).

As all hydrographic survey data has some degree of uncertainty, it is important to ensure that charted depths are accurate. The uncertainty of charted depth is factored into the allowance made for under keel clearance at the port.

A pre-dredge survey conducted well in advance of planned dredging operations enables a concise plan to be formulated. This process will ensure that previously dredged channels, berths, or construction works are maintained at their designated dimensions and design.

During dredging, progress surveys are conducted to verify dredging results and to measure the performance and efficiency of dredging equipment. Data analysis needs to be rapidly turned around to quickly identify areas that require further attention, for example, dredged areas which are still above design depth. Timely analysis is a huge factor in utilising the dredging time and allows for greater productivity.

A high accuracy post dredge survey is carried out to declare depths. Additionally, it is used to determine the maximum allowable draft for ships using the channel. This survey must be accurate and offer a guarantee of safe conditions. This is done through the detection of small objects which may pose risks to safe navigation and reduce navigable depths.

The execution of a complete surveying operation, from its inception to the final submission of the results, is a continuous process. All parts of which must be methodically and meticulously carried out if the full value is to be gained from it.

The most accurate and carefully gathered data will be wasted if not processed carefully. We make sure to collate and present data in a clear and understandable manner.

Investment in extensive survey data collection may at first appear to be costly. However, in the long term, quality surveys are worthwhile, as margins of error decrease which will directly lower overall costs.

“Hydrographic surveying accuracies are dependent on many factors. These include the quality of the sounding installation, the people operating the equipment and their ability to adjust to varying conditions.”

Neil Hewitt

PHS Managing Director

Contact us to understand how PHS can elevate your understanding and connection with the marine environment.