Pennsylvania regulators and officials from Range Resources Corp. are trying to determine what, if anything, caused a large water impoundment in the southeast part of the state to leak enough brine water that high levels of chloride were detected in the soil beneath it.

The discovery was made in April when Range employees pulled back the impoundment’s liner during a routine upgrade after it had been drained and cleaned. They noticed a “tell-tale white substance on the soil,” said Pennsylvania Department of Environmental Protection spokesman John Poister.

“There was some sort of leak there that we first felt resulted from a tear in the lining. Range is disputing this, but brine water got into the soil below, and a considerable amount of soil was contaminated by chloride,” he said.

Range said ongoing monitoring at the site has shown that the chloride levels have fallen since employees discovered the salty substance.

“These very low levels of chloride were found in an isolated region and do not present any significant environmental, health or safety issues,” said Range spokesman Matt Pitzarella. “We immediately notified the DEP and reported chloride levels in the soil and some chloride near secondary levels in the groundwater monitoring well at the immediate location. Other nearby groundwater monitoring wells do not exceed secondary chloride levels, which reflect potential issues with taste, color and odor.”

Poister agreed with Range and said the impoundment, located in Amwell, PA, about 40 miles south of Pittsburgh, is in a rural area with no nearby homes. He added that drinking water has not been threatened. The incident still prompted Range to hire an environmental remediation company and several thousand tons of the tainted soil have thus far been removed. Poister said that total could reach 15,000 tons by the time the cleanup is completed.

Although the impoundment has not been in use for almost a year, the incident is drawing attention as the pits have proved contentious in Pennsylvania, where some residents have reportedly complained of odors in some areas and the amount of time they remain in service before being reclaimed. The impoundments have been widely employed in both Pennsylvania and West Virginia and are considered crucial in the recycling and reuse process as operators utilize them to serve multiple wells in a single area.

The impoundment in question held roughly 15 million gallons, Pitzarella said, and was used to hold treated flowback water and fresh water. The site’s leak-detection system never showed any signs of seepage. At issue is what caused the fluid discharge.

Poister said the investigation revealed that the impoundment’s leak-detection system was crushed at some point, perhaps rendering it inoperational, while Range claims it was damaged during cleanup excavations. Range also believes that the waste could have come from a truck that had spilled near the impoundment months prior to the discovery.

Poister said the DEP has issued Range an “open notice of violation,” citing it for violating the Clean Streams Law and the Solid Waste Management Act. More citations could be on the way, he said, and civil penalties will be assessed after the cleanup is finished and both parties have a chance to discuss the violations. Poister added that it’s uncommon for leaks to occur at impoundments in the state.

“This is very atypical,” he said. “That’s one of the reasons we’re paying so much attention to this. We have not had that kind of problem in other impoundments, and we’re trying to determine what went wrong.”