Case Studies

Pipeline Bathymetric Survey

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The Background

Date: July2023-March 2024

Client: Northwest Marine

In July 2023, Storm undertook the first of ten site visits to the Gouthwaite Reservoir, Yorkshire to assist North West Marine with their installation of a new large diameter syphon pipe for Yorkshire Water. This facility serves as a vital water resource for the surrounding region and with increasing demands and aging infrastructure, there arises a need for better control of the water management system.

The coverage and precision required by the client meant that a number of Storms resources were called upon including the GeoSwath interferometric survey vessel for below water measurements, Trimble SX10 Scanning Total Station for above water observations and Trimble R12 GNSS antennas for accurate georeferencing of the data.

Process

The Challenge

An initial bathymetric survey ensured that all prior surveys on which the design had been based were still valid whilst the intermediate surveys provided accurate information on the progress of the dredging operation enabling modifications to ongoing dredging plans.

Once it was confirmed that the dredging had reached the desired design depth, Storm were called upon to assist with the sinking and final positioning of the 72m long, 2m diameter pipe to ensure that Yorkshire Water’s 50mm tolerance was met. This challenging requirement (the offshore end lay in 14m of water!) meant that innovative survey techniques needed to be found as the TVU (Total Vertical Uncertainty) of the GeoSwath system is around 100mm in ideal conditions. After numerous installation methods were discussed, a system using prisms mounted on pencil buoys under tension were the preferred method. This provided the most accurate system that allowed for continual monitoring of the pipe during installation and was also at a good cost. Horrific weather conditions (November in the North Yorkshire Moors!) during the pipe positioning created challenges that were overcome with good communication and collaboration and after two days the pipe was safely installed to the required accuracy.

A repeat of the intermediate bathymetric surveys then followed to monitor the backfilling of the dredged trench with regular monitoring of the pipe to ensure no movement and a return to pre-construction operations of the lake bathymetry. This was confirmed with a final survey once backfilling was completed including detailed mapping of the reservoir bed around the base of the Victorian dam wall to ensure no silt had been deposited around the sluice mechanisms.

Process

Results

The constantly evolving nature of this type of project effectively meant that Storm were on call for the entire duration of the undertaking with the requirement to mobilise at a moments notice and provide the client with up to date observations with which to plan the next stages of their operation. With some deft juggling of the work schedule, amenable staff and gruelling long hours, the project scope was met to the clients satisfaction and within their desired time frame and budget.

In addition, the data format requirements of the project expanded over its duration with different site engineers preferring alternative methods of displaying the acquired observations which Storm were only too happy to accommodate making full use of their suite of software, including the in-house developed GeoRiver® to provide comprehensible and coherent data sets. This was vital not only for the immediate client but also to effectively communicate results to other stakeholders who may not be fully conversant in bathymetric and topographic datasets.

“The services of Storm Geomatics were provided in good cooperation and the quality of the results and reports was to our entire satisfaction. We would recommend Storm Geomatics for their professionalism and reactiveness to any other customers seeking this type of service in the field of marine and inland water engineering.”