Eye in the Sky: Airborne Electromagnetic Survey

Photo courtesy of Geotech Ltd

BOPU 5-11-20

Starting Monday, May 11, 2020, residents of Laramie County may be looking to the sky west of Cheyenne as the City of Cheyenne Board of Public Utilities (Board) conducts an airborne electromagnetic (AEM) survey. The Board contracted with a firm that will be flying a helicopter towing a large hexagonal frame just above the ground.  This is to allow the Board to take a peek under the Earth’s surface to better understand the geology and aquifers in the area. The helicopter will fly over parts of Cheyenne’s groundwater wellfields located under sections of the Belvoir, King and Polo Ranches.

With around 28% of Cheyenne’s drinking water coming from groundwater wells within this area, this AEM survey will help provide a better understanding of the soil conditions that make the aquifer and how water recharges the aquifer.  Long-term sustainability of groundwater resources is key for Cheyenne’s drinking water. 

The AEM survey method has been in practice since the 1950’s, however, recent advancements in technology make using the data from the surveys easier and will allow the Board to see the geological changes and moisture (aka groundwater) within the wellfields. The AEM system consists of a large hexagonal frame that houses a sensor and instrumentation which sends low frequency radio waves into the ground, then measures the response through a receiver. The electromagnetic signals are far too weak to interfere with electronic or communications equipment like broadcast radio stations or ill effects to wildlife. The helicopter will follow a “lawn mowing” pattern over the groundwater wellfields in order to gather the best data possible.