Mechanical Scanning System for Dam Inspection

Tetra Tech has selected BlueView Technologies to provide detailed 3D multibeam scans of the outflow ‘draft' tubes of a significant Hydroelectric dam in Washington State to check for obstructions, scouring, and erosion. The outflow control doors were obscured and not accessible to be surveyed with traditional surface vessel-mounted multi-beam echosounder sonar. Tetra Tech chose the BV5000-1350 3D Mechanical Scanning System with a portable tripod for the project.

The BlueView BV5000 was deployed from a 12-foot aluminum boat, and lowered to the rocky reservoir bottom 65 feet below the surface. A total of seven individual scans were taken in less than 4 hours. The individual 3D scan data were immediately viewable. Accurate registration of scans into a single, 3D mosaic was quickly accomplished using BlueView's bundled, commercially available software to ‘snap' together overlapping BV5000-1350 data and to register those data with surface vessel mounted multibeam data.

Brent Johnston, Tetra Tech's Marine Mapping Group Senior Systems Specialist has stated that the final imagery and data were presented to the public utility that operated the dam. Mr. Johnston added: "The detailed data provided our clients with the information they were seeking about the conditions of the draft tubes and the surrounding area. The BlueView BV5000 is a real asset for this and similar applications. We foresee many ways to utilise these systems with our hydroelectric, as well as our other nearshore and offshore clients."