It appears the dispute over how much to clean up contaminated groundwater in the North Pole area will continue into the new year. Officials with the state’s environmental regulatory agency are still reviewing studies to help them decide on a safe cleanup level for the chemical that leaked from a North Pole refinery into the area’s groundwater.Download AudioOfficials with the state Department of Environmental Conservation suggested last fall that DEC Commissioner Larry Hartig may issue a decision on a cleanup level for groundwater contaminated with the industrial solvent sulfolane around the end of the year.But DEC environmental program manager Bill O’Connell says that’s unlikely to happen.The cleanup plan announced Monday requires Flint Hills Resources-Alaska, and potential future owners of its North Pole refinery, to continue remediating and removing contaminants from the facility. (Credit KUAC file photo)Sulfolane leaked for years from the North Pole Refinery now owned by Flint Hills Resources-Alaska. Flint Hills closed the refinery last summer, citing increasing costs, including those related to the sulfolane cleanup. A portion of the facility is now used as a fuel terminal.“Currently, there is no estimate for when DEC will issue a final cleanup level for sulfolane,” he said.It’s a complex issue, made even more so because there’s no accepted standard for how much sulfolane a human can be exposed to before it poses a threat to health.O’Connell says DEC officials are continuing their analysis of data as part of the review of a DEC staff recommendation for a stringent cleanup level of 14 parts-per-billion. Hartig agreed to the review in April in response to a request by Flint Hills Resources-Alaska. Flint Hills owns the North Pole refinery that leaked sulfolane into the groundwater, apparently before it bought the facility in 2004.Flint Hills officials suggested a year ago that DEC should instead set a less-stringent cleanup level that would allow 25 times more sulfolane than the agency’s recommendation.O’Connell says much of the data that DEC is weighing on the subject was presented during a two-day session in September by a panel of experts the DEC asked to look into the issue. The experts with Ohio-based Toxicology Excellence for Risk Assessment, or TERA, focused on studies on reference doses for sulfolane. That refers to the maximum amount of a toxic substance that can be ingested before it poses a risk to human health.“Those discussions were in regards to the reference dose, which is one factor of a number of factors that go into calculating a cleanup level for sulfolane,” he saidO’Connell says a report on the two days of discussions has been posted to the TERA website.