Water tested at a pair of contaminated Airway Heights wells contains chemical concentrations more than 15 times greater than thresholds established by federal regulators, according to city officials. The Environmental Protection Agency has established a limit of 70 parts per trillion for chemicals, known by the acronyms PFOA and PFOS, that were used for decades in fire-retardant foam at a fire training site on Fairchild Air Force Base. Two wells tested in Airway Heights showed levels above 1,100 parts per trillion, City Manager Albert Tripp said. The wells have been shut off from the system as part of a flushing process that is expected to last until at least Monday, when the city will again test its supplies for traces of the chemicals. The levels established by the EPA are not enforceable under any federal law, and the Spokane Regional Health District stresses that the link between exposure and potential health problems is not yet completely understood. Airway Heights is pumping water into its system from Spokane to meet demand during the flushing period. The city has been releasing potentially contaminated water from hydrants in locations that would minimize any new contamination, including spraying it in areas where city irrigation has been occurring for years, Anderson said. “We’re trying to discharge it onto city properties as much as possible,” Anderson said. Fairchild has lent its assistance in handing out bottled water to affected citizens, but several former and current city officials say the base could be providing additional water…