filter socks
7:24 am
Mon April 28, 2014

Explaining "NORM" and "filter socks"

For many North Dakotans, the terms “Norm” and “Filter Socks” may sound strange.

But the two terms are at the center of concerns over illegal dumping of those socks. A number of the socks were discovered at an abandoned gas station in Noonan. The investigation into that dumping continues.

To get a handle on what these terms mean, Prairie Public's Dave Thompson turned to two experts at the Energy and Environmental Research center at UND.

“Filter socks are something that is usually associated with the pumping system on an injection well,” according to John Harju, the associate director of research for the EERC. “Most of the produced water, or frac-flowback water from Bakken wells in our state, is reinjected into the deep subsurface. In the interest of keeping fine particulate matter that may be suspended in that water solution, you put these long filters on that injection tubing to filter out those fine particulates.”

In that filtering process is “NORM” –“Naturally Occurring Radioactive Materials.”

“ And really what happens in one of these socks is relatively small amounts of radioactivity will be concentrated because you end up with many of these tiny particles all in one place," said Harju.

“NORM that we unearth from drilling wells in the Bakken or from the water produced in the Bakken is really no different than what you find around your house,” said EERC senior research manager Jay Almlie. “Cat litter, for example, is a good one to pick on. Cat litter is radioactive at roughly the same levels as most of the NORM materials we are discussing.  So are Brazil nuts, that we like to eat from mix nut cans.”

But Harju says the EERC is not advocating what some of the companies have done with the dumping of the filter socks.

“Certainly that’s not acceptable," said Harju. "And certainly, the companies that we’re dealing with are doing everything they can to eliminate that sort of activity from occurring.”

The socks cannot be dumped in North Dakota landfills – because none of them are licensed to receive the socks. Instead, they have to be shipped out of state.