Case Study: Advancing Underwater Dam Inspections with UAI, SEAMOR, and Voyis

Underwater Acoustics International (UAI), a leader in underwater inspection solutions, recently undertook a ROV – 3D Photogrammetry & hydrographic survey of a hydro dam’s stilling basin and tailrace with a focus on the toe to detect any potential undermining or undercutting. This survey was part of a critical infrastructure inspection aimed at ensuring the structural integrity of the dam, a vital component of the local infrastructure responsible for water management and power generation. The dam required evaluation for potential structural vulnerabilities, with the client needing detailed insights into long-term safety and regulatory compliance requirements. 

The project was crucial for identifying any erosion or damage to the underwater foundation of the dam that could compromise its stability. Such issues, if left unaddressed, could lead to costly repairs or, in the worst-case scenario, a failure that would pose risks to downstream communities and infrastructure. The inspection was also essential for fulfilling regulatory requirements set by the US Federal Energy Regulatory Commission (FERC), which mandates routine, in-depth inspections of dam structures to maintain safety and operational standards. 

Navigating the Complexities of Dam Inspections

Dam inspections present a host of challenges, stemming not only from demanding environmental conditions but also from the complexity of capturing accurate data across expansive and often inaccessible underwater areas. Rocky terrain, strong currents, and low visibility further complicate operations, while regulatory standards set by the U.S. Federal Energy Regulatory Commission (FERC) demand precise and highly detailed data to evaluate the structural integrity of hydroelectric infrastructure—raising the bar for inspection capabilities. 

Inspecting submerged structures like concrete walls and natural rock formations requires a level of visual detail and spatial accuracy that conventional tools often fail to deliver. The ability to generate accurate 3D models from survey data becomes essential for identifying erosion, deformation, or structural degradation over time. However, traditional sonar systems—particularly when deployed from uncrewed surface vehicles (USVs)—have limitations in capturing these features. Acoustic signals typically reflect off the nearest surface, making it difficult to detect features hidden beneath overhangs or in recessed areas. Moreover, the resolution of sonar is insufficient for detailed structural assessment, especially at the toe of the dam where failure risk is highest. 

In addition to geometric limitations, turbidity poses a significant challenge to visual inspection. Suspended sediments, biological matter, and organic debris in the water can obscure visibility, rendering standard video and still cameras ineffective. These conditions often result in low-quality imagery and incomplete datasets, delaying project timelines and reducing confidence in inspection results. 

The Voyis Discovery Stereo Camera was specifically designed to overcome these visual and environmental limitations. Its synchronized LED lighting and advanced optical design enhance image clarity in turbid conditions, enabling reliable data collection even when visibility is severely reduced. By capturing stereo image pairs, the system generates high-resolution 3D point clouds that accurately represent underwater structures in their true geometry. This capability was critical to the UAI team, who used the data to extract precise measurements and create complete photogrammetric models that satisfied FERC’s rigorous standards. 

With its BV-certified accuracy, the Discovery Stereo Camera ensured that all data collected could be trusted for decision-making and regulatory compliance. The certification further validated the system’s reliability, giving stakeholders confidence in the results and establishing a new benchmark for underwater dam inspections. 

Why Voyis?

UAI turned to Voyis for the Discovery Stereo Camera with Voyis VSLAM Powered by EIVA NaviSuite technology to overcome the visibility challenges posed by the dam’s submerged and murky environment.  

While sonar systems can provide depth measurements, they lack the visual detail and clarity required to fully assess the condition of the dam’s structures, and limitations as overhangs can block acoustics beams.  

Voyis’ optical system filled this gap by offering detailed, high-definition visual data that could be used to assess the structural integrity of the dam and its surroundings. The 3D models produced by the camera provided highly accurate spatial data, allowing UAI to measure critical distances and angles without the need for invasive physical inspections. Additionally, the integrated VSLAM solution ensured complete area coverage throughout the survey, supporting the generation of comprehensive photogrammetric models. Real-time data coverage feedback further streamlined operations, minimizing survey inefficiencies and reducing standdown times for the hydro plants. 

SEAMOR ROV’s Maneuverability and Efficiency

Another key element in the success of the project was the maneuverability of the SEAMOR Chinook ROV. Known for its agility and adaptability in confined and challenging environments, the SEAMOR Chinook ROV excelled in navigating the tight spaces and rocky outcrops of the dam. Its compact design and precise control systems allowed the UAI team to inspect hard-to-reach areas of the dam that would otherwise be inaccessible. This maneuverability was critical in ensuring the inspection covered the full extent of the structure, capturing comprehensive data in a single, efficient mission. 

Successful Outcomes and Client Satisfaction

Despite the difficult conditions, the collaboration between UAI, Voyis, and SEAMOR resulted in a complete and accurate dataset that met the stringent requirements of the client and regulations. The Discovery Stereo Camera’s high-quality visuals and the Voyis VSLAM Powered by EIVA NaviSuite’s ability to provide real-time feedback allowed for near-perfect coverage of the dam’s toe, with all critical areas captured in astonishing detail. The client was extremely satisfied with the results, ultimately leading to additional projects based on the proven success of the solution. 

Key Takeaways 

• Seamless Collaboration: The combined efforts of Voyis, SEAMOR, and UAI showcased the strength of industry partnerships in tackling complex inspection challenges. 

• Technological Synergy: The Voyis Discovery Stereo Camera’s high-resolution imaging and VSLAM solution, integrated with the SEAMOR ROV, delivered superior visual data and enhanced operational efficiency. 

• Maneuverability Matters: The SEAMOR ROV’s ability to navigate tight and rugged underwater environments was essential for accessing critical areas of the dam. 

• Data Quality: The ability to generate accurate 3D models and take precise measurements directly from the visual data was crucial for compliance with regulatory standards and client satisfaction. 

• Visibility Solutions: Voyis’ technology enabled UAI to overcome significant visibility challenges, providing detailed and reliable visual data where sonar solutions alone were inadequate.