James Cannia, a senior geologist with Aqua Geo Frameworks of Mitchell, presented results from an aerial survey at a recent meeting at the Veterans of Foreign Wars hall in Creighton.
Aqua Geo Frameworks staff conducted the aerial electromagnetic survey flights over the Bazile Groundwater Management Area last July, flying out of the Creighton airport.
On March 15, the Bazile Groundwater Management Area staff, on behalf of the Lower Niobrara, Lewis and Clark, Lower Elkhorn and Upper Elkhorn natural resource districts, hosted the meeting to present results from the survey.
Aqua Geo Frameworks was responsible for collecting flight data and analyzing it. Cannia presented the final results to a group of more than 50 crop producers and community members of Creighton and surrounding communities.
Cannia first explained how the AEM equipment worked. In short, a hoop that is hung below a helicopter sends a pulse of electrical signal into the soils and rocks below, which energizes the material. The material then sends back a characteristic signal which is recorded, and can be interpreted to determine the soil composition (sands, clays, silts, gravels, etc.). This data is taken together with borehole soil classification data from the area that was gathered by University of Nebraska-Lincoln Conservation Survey Division, to determine what type of soil is likely represented by the flight data.
Once the data is pieced together, the areas where errors were detected, such as areas with steel structures like pipes, or power lines, were removed because the equipment was unable to read the soil due to those obstructions. Then the data is placed over a map of the area to help reveal general trends, showing the flightline’s three-mile square grids.
He said the readings were only completely accurate within a small area surrounding each flightline, because the areas between the flightlines were not measured.
The grid was closer together in the wellhead protection area southeast of Creighton, flightlines were flown only one-half of a mile apart in an effort to enable three-dementional mapping of ground formations and shallow aquifer material. Another area flown on the one-half mile pattern was the area southwest of the well field of the West Knox Rural Water District.
The NRDs intend to use the data to make better-informed management decisions, and to allow areas that would be particularly sensitive to pollution to be managed and monitored more closely, in order to speed the recovery of the groundwater quality for the area residents, according to Tanner Jenkins of O’Neill, BCMA project coordinator.
“This data will also provide a solid wide scale foundation for existing datasets, and future datasets to build on to increase our knowledge of the area’s groundwater,” said Jenkins. “The NRDs will be making Google Earth files available for the public to download and access at their convenience, as well as make available the slide show presented at the meeting for those who were unable to attend, or would like to review the information presented.”
The materials will be linked or available from the participating NRD websites in the next few weeks.