A metal detector, waders and a robot named Elvis: a culvert inspection story

By Joe Calabro

When you’re on a state highway, it’s easy to see certain hazards like potholes or debris. Things get complicated when an issue lies below the road’s surface in one of the thousands of culverts that carry water, and sometimes fish, beneath a highway.

That’s where Chau and Elvis come in.

Chau Nguyen joined our agency in 2021 as an intern with a degree in Environmental Engineering. She enjoyed working with an experienced team and eventually accepted a job as a stormwater and drainage engineer.

Chau Nguyen (right) tests Elvis the robot before sending it in for a culvert inspection

She now leads the culvert inspection program in our King/Snohomish/Skagit/Whatcom area, assessing maintenance work and identifying how to avoid emergency failures of the roughly 14,000 culverts in that area. How does Chau do it? With a robot.

Elvis is her robot’s nickname. The remote-controlled vehicle allows Chau to explore drainage infrastructure that would otherwise be inaccessible.

“Roadway drainage is like a tucked-away underground world that people aren’t aware of – it keeps the traveling public safe,” she said.

Elvis the robot is outfitted with a camera in the front and two headlights to illuminate any obstructions. The corded connection is more reliable than wireless and allows Elvis to be retrieved if inactive.

These inspections pay huge dividends. Rust, corrosion or leaks can lead to culvert failures. A collapsed culvert can require immediate lane closures , and costly reconstruction that can be inconvenient for travelers and freight movement. Moreover, fish migration and other environmental impacts can occur.

In the field

On a recent inspection below State Route 99 in Lynnwood, the purpose of the mission was two-fold: inspect the condition of the culvert and obtain measurements for a new fish passage to be designed in the coming years.

Ryan, a member of our maintenance team in the area, donned his waders and climbed about 10 feet down into the catch basin where he was greeted by knee-high water. Elvis, weighing about 75 pounds, was lowered down to him. Our maintenance teams do regular culvert inspections, looking for obvious blockages or collapsed areas. If they notice an issue, they flag it for Chau (and Elvis) to do an in-depth inspection.

Chau drove the robot through the 36-inch diameter culvert. The feed transmitted back to her is always well-lit and clear thanks to its headlights.

A crew on the other side of the road located a catch basin hidden by gravel. Using old plan sets, they set to work with a metal detector, shovel and broom. They dug up the utility cover in minutes and bragged about their discovery from across the road as any good treasure hunter should.

Chau uses Elvis’ mounted camera and headlight to maneuver the robot through the culvert (left).
A still image from the inspection recording (right).

The team confirmed the culvert’s alignment, material and length and didn’t find anything of major concern. Measurements were taken at each catch basin and the process was repeated at the culvert’s outlet. The robot’s recorded footage can be used for future reference.

The length of a culvert on SR 99 in Lynnwood was measured by marking the length of cable used by Elvis.

This season’s rain and snow will send water flowing through our culverts. Monitoring their conditions will ensure infrastructure is appropriately maintained and safe for travel

Job opportunities

Four different work groups were represented at the culvert inspection on SR 99: Maintenance, Environmental, Fish Passage Design Engineering, and Communications. It’s a small slice of the different fields and career opportunities we have to offer. Check on job openings at our careers webpage and learn more about the benefits that come with working with us.