College of Liberal Arts and Sciences at Iowa State University

Prospecting for gravel

Igor Beresnev uses modern geophysics to replace old-fashioned method of hunting for gravel.
It's the old fashioned way to find gravel deposits. Hire a drilling company. Use a little common sense and try to find the much-needed mineral.

That system has been ongoing for many years.

Igor Beresnev, associate professor of geological and atmospheric sciences, says that the old-fashioned way may be outdated.

Beresnev and his research team have recently published a paper in the Journal of Applied Geophysics that uses modern technology for rapid reconnaissance surveys for gravel and sand accumulation.

Natural aggregate (gravel) resources are used extensively in local-road maintenance and construction. Most local municipalities face a constant need for the replenishment of diminishing reserves. The gravel must also meet certain quality and size standards as it must be firm enough and rigid enough to withstand vehicular traffic.

"A couple of years ago, Story County was running out of reserves of gravel and sand that they needed for secondary road repair," Beresnev said. "They wanted to explore new sites of excavation and wanted to know if there was a better way of locating these deposits."

Working with the Iowa Geological Survey, Beresnev looked at ten potential locations in Story County where significant accumulations of gravel and sand might be located based on surface expressions.

Beresnev and his team utilized a 24-electrode resistivity imaging apparatus to conduct fast and accurate surveys of those locations.

"We calibrate the method at an excavated site with the known gravel-layer geometry, and then apply it to surveying the sites of suspected but unknown potential," Beresnev writes.

Of the ten potential sites, only two of those proved to have significant accumulations of sand and gravel.

"While the other sites had some sand and gravel deposits, we were looking at mass quantities of these minerals to make it economical to transport," Beresnev said. "A county such as Story County needs thousands of tons of gravel to fulfill its needs for several years for road maintenance."

Finding the gravel and sand deposits is just one aspect to Beresnev's research findings.

"Not only did we need to locate it, but we were able to provide accurate estimates of the volume of the deposits," he said. "And it costs almost nothing to get this information.

"This technology is cheap, fast and accurate. It would have taken a drilling company several days and thousands of dollars to find out the data we collected in just one day."

Beresnev confirmed his findings by drilling into the two gravel deposits.

"I'm very optimistic about the potential of using this technology in the future," he said. "I think we have solved a very practical problem. Sand and gravel are the number one mineral resources used in this country outside of oil."