
ASI Marine L.P. (ASI) completed an underwater inspection project at Dillon Dam and the Roberts Tunnel Intake, located in Summit County, Colorado. Contracted by Denver Water, ASI undertook this project to evaluate the condition of critical infrastructure components, ensuring their continued functionality and safety.
Project Overview
The primary objective of this project was to inspect the inlet structure, trash racks, and horizontal slide gate at Dillon Dam’s outlet works. Similarly, the Roberts Tunnel intake required an assessment of its inlet structure and trash racks. These inspections were essential for maintaining the integrity and operational efficiency of the dam and reservoir systems.
Innovative Approach with ROV Technology
ASI’s innovative approach set this project apart. Instead of employing traditional methods that involve commercial divers and corresponding deep-water dive spread, ASI utilized a remotely operated vehicle (ROV). This choice not only enhanced safety but also increased efficiency and reduced operational costs.

The Seaeye Falcon ROV
For this project, ASI selected the Seaeye Falcon ROV due to its exceptional capabilities and compact size. This advanced ROV was customized specifically for the Dillon Dam application. Key features included:
- Imaging Sonar: Mounted on the Falcon ROV, this two-dimensional sonar provided real-time plan view information, crucial for navigating and inspecting underwater structures.
- High-Resolution Camera: For detailed inspections of the horizontal slide gate at the Dillon Dam outlet works, ASI used a custom-built high-resolution, low-light, color ethernet camera. This camera was mounted below the ROV, ensuring clear and precise visual assessments.
ASI Marine’s field and engineering team should be commended for their ability to not only acquire detailed video/sonar of the operating slide gate, but also for their ability to think outside-the-box and develop a camera/boom system to avoid the costly marine construction component of this project. We would be pleased to have ASI Marine work with Denver Water on any future underwater inspection and marine engineering projects.
– Denver Water Project Manager
Inspection Process and Deliverables
The inspection process was thorough and meticulous. ASI conducted visual inspections, focusing on the following key components:
- Outlet Works Structure: General condition assessment through visual inspection.
- Trash Racks: Detailed evaluation to ensure they are free from blockages and in good condition.
- Horizontal Slide Gate: Observed during three full opening and closing cycles to assess its operational functionality.
For the Roberts Tunnel intake, the process was similar, with a focus on the inlet structure and trash racks

Delivering Comprehensive Results
ASI’s commitment to quality and precision was evident in the deliverables provided to Denver Water. These included:
- Written Inspection Report: A detailed document outlining the findings and condition of the inspected components.
- Inspection Logs: Comprehensive records of the inspection process.
- Video Stills and DVDs: Visual documentation of the inspections, offering clear and direct insights into the underwater conditions.
Conclusion
The successful completion of this project at Dillon Dam and the Roberts Tunnel Intake underscores ASI Marine’s expertise and innovative approach to underwater inspections. By leveraging advanced ROV technology, ASI not only met but exceeded the project’s objectives, ensuring the continued reliability and safety of these critical water infrastructure systems.
If you have questions about ASI’s underwater inspection services or want to learn more about this project, please contact Drew Michel at dmichel@asi-group.com or (512) 761-0292.
*Featured Image of Lake Dillon: Unedited image by Hogs555. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
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