Toston Dam Hydrographic Surveys

Norbit Multi-Beam Sonar mounted to vessel used for hydrographic survey

The objective of the Toston Dam Hydrographic Surveys was to investigate conditions in the immediate vicinity of Toston Dam on the Missouri River in Montana where diving operations had failed to accurately map conditions due to limited visibility.

The Toston Dam Hydrographic project was completed in two segments.  Both segments required high resolution, high frequency multibeam and dual frequency single beam sonar bathymetric survey mapping.

The downstream portion consisted of the hydrographic survey of the tailrace area.

The upstream portion included surveys of both the canal inlet jetty and the upstream face of the dam.

This data was then used to characterize the subsurface for identification of scour (including indications of active springs), reinforced concrete degradation, sediment buildup, and riprap/jetty degradation. The intent was to identify locations requiring remedial work and provide high resolution mapping for monitoring conditions in the future for maintenance and design planning.

This is a snap shot of the survey. Colors represent depth with red as shallowest to blue as deepest. Sonar data was then used to develop TIN surfaces in AutoCAD Civil 3D for development of contours.

For this project UMS performed the following activities:
• developed survey plan
• mobilized equipment and personnel to project location
• conducted hydrographic survey of downstream side of dam
• reduced data, prepared CADD and 3D digital color maps, conducted a limited interpretation with focus toward achieving goals of survey
• report preparation summarizing findings, discrepancies, and recommendations
• quality assurance review of data and plans
• registered professional engineer of record seal to certify final submittals
• reviewed results with the design team and assist in further interpretive efforts

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