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Using Drones to Identify Contaminated Groundwater Seeps

A drone lifting off of a boat over Lake Margrethe as an EGLE staff person looks on

Using Drones to Identify Contaminated Groundwater Seeps

The use of aerial drone technology is a new and evolving tool that enables staff at the Michigan Department of Environment, Great Lakes, and Energy (EGLE) to do their work in a more efficient manner. The drones provide more accurate, complete, and new site data on environmental projects, including PFAS investigations.

In January 2018, EGLE created a special team called the Drone Technical and Program Support (TAPS) team. The purpose of this team is to establish best practices and monitor the use of this new technology throughout all divisions of EGLE.

Infrared Light

With the naked eye, we can see many different types of light. Our brains see these different lights as the visible spectrum, or colors, from red to violet. Infrared is a form of light that falls just beyond the color red on the visible spectrum. Since infrared is not in the visible spectrum, it is invisible to the naked eye. Even though we cannot see infrared light from a hot piece of metal like a soldering iron, we can feel infrared light on our skin as heat as we bring our hand close. The special cameras on the drones EGLE uses can help us see infrared light in the environment.

The two images below were taken seconds apart. The first is a regular photo, showing what we can see with the naked eye. The second is an infrared image, showing the temperature of the environment in the frame. Hotter temperatures appear as yellow, red, or white. White is the hottest temperature – note how the team’s bodies are mostly white and red. Colder temperatures show as green, blue, or somewhere in between. Blue is the coldest – note how Lake Margrethe in the background is a deep blue as the lake gets deeper.

Using Drones to Assist with PFAS Response

The drone currently used for the PFAS response is equipped with Forward Looking Infrared (FLIR) and regular cameras, and can capture normal, zoomed, and infrared thermal photos and videos. Drones are used to identify where underground chemical contamination that has affected the groundwater may be leaking into a stream or a lake. Lakes and streams in Michigan can range from 70° - 90° F, especially in summer. Groundwater that is seeping out can range from about 50° - 55° F. This temperature difference can be “seen” by the infrared camera, and the location can be mapped for follow-up investigation. Under a normal camera lens, this temperature difference is not visible.

EGLE is believed to be the first in the nation to use a FLIR-equipped drone to search for groundwater seeps that may indicate locations of PFAS contamination. This innovative use of technology is another example of Michigan’s proactive approach to addressing this emerging contaminant.

In the video below, the dark blue represents colder groundwater seeping into the warmer open waters of Lake Margrethe. Water is moving from the top of the screen towards the bottom.

PFAS contaminated ground water seeping into Lake Margrethe, via forward-looking infrared camera.

Infrared video of contaminated groundwater seep

In the video, the ground is colored green and blue; the blue represents the cold groundwater underneath the ground. The shoreline is a mix of green (ground) and red/orange (water).

The water is red and orange because it is warm -- in the summer the lake temperature can get as high as 90°.

The dark blue represents colder groundwater seeping into the warmer open waters of Lake Margrethe. Water is moving from the top of the screen towards the bottom.

Drones can be used at locations where there is known PFAS contamination and it is suspected that PFAS may be coming from an underground plume from a nearby site with known groundwater contamination. EGLE gathers both videos and photos from the drone. As of early December 2018, two flights have occurred at PFAS sites in Michigan. One flight occurred at Lake Margrethe, in Grayling, on September 18, 2018. The other flight occurred at Van Etten Lake in Oscoda on November 9, 2018.

Before EGLE flies a drone over private property for an environmental investigation, staff reaches out to the property owner for permission. However, in emergency situations (such as a response to a pollution emergency), and where EGLE is authorized by law, license, permit, or other legal mechanisms, permission is not required. Permission is also not required over public property.

The video and images are reviewed thoroughly by EGLE staff to help determine next steps in an investigation. The entry of colder groundwater does not confirm the presence of PFAS contamination; it allows EGLE to better target sampling efforts. Identifying the flow of groundwater into a lake may also assist in effective placement of treatment, if needed.

EGLE may also use hand-held infrared cameras while standing on land to gather additional information when conducting a drone flight. These infrared images look different than the aerial photos from the drone, however, many concepts in the images are the same. Below is an explanation of the infrared imagery collected while standing on the shore of Van Etten Lake.

PFAS Drone Image - Handheld Infrared Explanation