Salina A groundwater sample taken at Kansas State University's Salina campus contained a nearly 10 percent solution of a toxic solvent that has been linked to birth defects and cancer.
The sample taken last month contained 800,000 parts per billion of trichloroethylene, much higher than previous tests. The maximum concentration of trichloroethylene, or TCE, allowed in drinking water is 5 parts per billion.
The concentration was so high that a pilot study that was to deploy bacteria to clean it up will have to be modified.
"Concentrations above 100,000 are toxic to microbes," the U.S. Army Corps of Engineers wrote in a memo to local officials. "Therefore, bioaugmentation will not be an effective treatment method at the current concentrations."
The corps now plans to use chemical remediation to break up the concentrated TCE, followed by microbes to eliminate the partially reduced compounds.
TCE, a compound widely used in solvents during World War II, likely originated from the former Schilling Air Force Base. It closed in 1965, and the grounds eventually became home to the K-State satellite campus.
Though the highest concentrations of TCE have been found near K-State buildings, elevated levels also have been found in groundwater east of Interstate 135.
Katie Mayes, a spokeswoman for the Salina campus, said the school's drinking water comes from the city, and the city's water supply is not contaminated. She said estimates on how quickly the contamination could reach city wells vary from eight years to 120 years.
"But it's not a problem at this point," she told The Associated Press on Thursday. "The water is safe."
The monitoring well from which the highly concentrated sample was drawn has been in place since at least 1997. One sample drawn in 1999 contained 103,000 parts per billion of TCE, but samples since then have been generally declining. A sample drawn in 2004 contained 1,392 parts per billion of TCE.
Robyn Kiefer, who is managing the corps' cleanup efforts at the former base, downplayed the sudden spike.
"You always see groundwater fluctuations," she said.
For instance, cracking of subsurface clay can cause pockets of contamination to dislodge, altering the concentration.
But an assessment early this year by the U.S. Environmental Protection Agency warned that the monitoring wells were so poorly placed that they could easily fail to detect some contamination.
The corps will install temporary monitoring wells - one shallow, one deep - at nine locations near where the high concentration was found to better determine where it is.