The sUAS Guide Issue 02, July 2016 | Page 16

When a conservation agency needed accurate data on a crumbling dam too treacherous for human access, they relied on an unmanned aerial system

Too Dam Dangerous?

When dilapidated structures are too dangerous for human access, UASs provide a safe, cost-effective way to complete surveys and inspections.

Just 20 minutes south of a bustling metropolis, along a broad canal, is a popular bike path that offers a peaceful refuge from city life. Here, locals and tourists enjoy a stretch of quiet waters, green fields, and trembling aspens.

Set in a particularly tranquil location, the shores near the dam provide the perfect spot for a rest or picnic – perfect except for the glaring danger signs.

Built in the 1930’s, the retired dam is now in crumbling condition. As a result, the dilapidated dam causes a wide range of ecological, functional, and aesthetic problems, but the biggest concern is safety. While red and yellow signs posted all over the structure caution visitors to stay away, it is common to see people climbing and fishing on the dangerous dam.

When an enormous slab of concrete broke from the dam and slid into the canal, an agency in charge of protecting these types of places and structures knew they had to take action to ensure the safety of visitors and avoid legal risk. They decided to begin the process of restoring and converting the dam into a safe, usable walkway.

The first step was to open up a request for proposals from engineering firms. But there was a problem. To solicit design ideas and cost estimates, they would need accurate measurements and a three-dimensional model of the dam. How could they achieve this, when the dam’s life-threatening condition made access too risky for traditional survey methods?

By foot, by boat, or by traditional aircraft?

The dam was too old and fragile to inspect by walking on it, so the preservation team began considering other methods of inspection. One option was to use a small boat, but it was quickly determined this would not work, since measurements of the top of the structure were needed. A helicopter could provide the necessary aerial views, but the costs would be tremendous.
They decided to seek out estimates to collect the data and photos they needed via an unmanned aerial systems (UAS), or drone.

“When this client contacted us, we’d never surveyed a dam,” explained Sebastien Long, sales manager for microdrones. “It was a huge job that would involve many challenges and flight hours, but we knew we had the technology to achieve their goals.”