In the summer of 2011, the DEP collected and analyzed sediment from the PA Brine wastewater treatment plant in Indiana County and found levels of radium 226 in the discharge pipe that was 44 times the drinking water standard. Twenty meters downstream of the discharge point, levels were still 66 percent above the standard.
Similar results were found at several other facilities, as revealed in a settlement between the Environmental Protection Agency and the company earlier this year.
In April 2011, the PA Brine plant and all such plants in the state had been told not to accept Marcellus wastewater, but the radioactive elements found in PA Brine's soil were remnants of prior discharges.
Kelvin Gregory, an assistant professor at Carnegie Mellon University who works on Marcellus water issues, said the peak of radioactivity in wastewater comes after the initial gush of flow-back water comes to the surface after fracking. Radium concentrations are highest in produced water, a term that describes the brine that continues to flow out of the well for long periods of time after that well starts producing gas.
In a survey of flow-back and produced water at 46 Marcellus sites, Gregory found radioactivity increases for two months on average, then he saw plateaus.
Whether the level stays at that high concentration forever or tapers off at some point isn't yet clear, Gregory said. The wells haven't been producing long enough to tell.
Examples of highly radioactive waste from the Marcellus are rare so far.
"The cases where we get a very hot load are very few and far between," said John Poister, a spokesman for the DEP's southwestern district.
But every once in awhile, it happens.
In April, a truckload from Rice Energy arrived at Max Environmental's Yukon Landfill in Westmoreland County and set off the alarm. The waste was deemed too radioactive.
The company shopped it around to a few landfills, but no one would take it, Poister said. Eventually, the truck went back to the source while arrangements were made to transport the waste to a specialized disposal site in Idaho.
Why was Rice's load so much hotter than others?
"That's a question for the (DEP) study," Poister said.
"We've taken quite a bit of drill cuttings at our Yukon facility this year, and only one truck triggered the radiation alarm," said Carl Spadaro, environmental general manager of the Yukon landfill. "Other landfills have had alarms triggered quite a bit."
Yukon accepts about 90,000 tons of waste annually and just last month amended its permit to be able to accept waste that trips radiation alarms.
"We didn't do this to bring in a lot of [radioactive] waste," Spadaro said. "We did this to level the playing field."
Yukon competes with two other landfills within a 5-mile radius.
"The biggest concern is exposure of a landfill worker during unloading and somebody who's handling material," Spadaro said.
The exposure level allowed at Pennsylvania landfills is a quarter of the EPA's public radiation dose limit of 100 millirem per year.
"This is equivalent to about two chest X-rays," said Kevin Sunday, a former spokesman for the DEP.