The Department of Environmental Conservation announced earlier this week that tests of samples from two community drinking wells in Salcha indicate that the water is safe to drink.

The department tested both the well at the Knotty Shop and the Salcha Community well at the fairgrounds following the discovery of improperly disposed of foam waste at the nearby Rolling Stone Gravel Pits. The department has identified 38 private properties with a quarter-mile radius of the incident site and a contractor is now in the process of contacting homeowners to test the drinking of water of any private wells in the area.

“We’ve completed testing on the two public drinking wells. Both of those wells came back clean,” said Sarah Moore, a state environmental program manager who is serving as on-scene coordinator for the response. “If there are people concerned about using their private wells until we do that sampling, in the meanwhile you can use the community wells.”

The department has, however, found that waste in some of the remaining totes at the gravel contain perfluorinated compounds — known as PFOS — and “levels of ethylene glycol in exceedance of the state groundwater cleanup levels.”

Moore said that, once drinking water in the area is deemed safe to drink, the department intends to move on to identifying any possible environmental contamination.

“I think one of the next things we’re expecting from the Air Force is to put together a plan to start sampling the groundwater at the Rolling Stone Gravel Pits,” Moore said. “That will give us a much better idea of whether or not we need to focus on clean-up actions.”

The Air Force is involved because the foam waste initially came from Eielson Air Force Base. In early May, the state and the U.S. military reported that 33,000 gallons of Ansul Jet-X 2% High Expansion Foam waste had been improperly disposed of at two gravel pits owned by Rolling Stone Inc. The waste was generated at Eielson Air Force Base as a result of fire suppression system testing.

According to the most recent incident report, released Monday, the department now estimates that the total volume of waste improperly disposed of is closer to 53,000 gallons.

According to Moore, the total estimated volume of the foam concentrate used during the testing and improperly discharged remains unchanged. The estimated total volume of the waste was increased because an Army Corps of Engineers investigation determined that potable water used to clean hangers was later mixed in with the other waste, following the tests.

“The concentrate volume hasn’t changed,” Moore explained.

The department is currently testing samples taken from all 46 totes at the gravel pits for other chemicals that might be present in the waste.

“The waste was generated from a number of projects on Eielson and then it was transported off Eielson in tanker trucks or in these big totes,” Moore said. “There’s about 12,000 gallons (of foam waste) that’s still in totes on the property. So we’ve been sampling those totes to get an idea of what the material that was poured into the ground looks like chemically. We haven’t gotten all of those sample tests back yet.”

According to the incident report, lab results received by the department on June 16 indicate that some of the waste in totes contained levels of ethylene glycol, which exceed state groundwater cleanup levels. Moore said that wasn’t surprising, because that’s one of the ingredients in the foam concentrate.

Additionally, six totes were sampled for fluorinated compounds. Thus far, the department has received results back for three of the totes; these indicate that one of the totes contained perfluorooctane sulfonic acid exceeding the state cleanup level.

There is no additional discharge occurring at the site and an investigation into how and why the waste was improperly disposed of remains ongoing.

Contact staff writer Alistair Gardiner at 459-7575. Follow him on Twitter: @FDNMoutdoors.