A NASA-funded treatment plant in Pasadena has removed hundreds of pounds of toxic residue left over from the Jet Propulsion Laboratory's early rocket-building days.

The $8.5 million Monk Hill water treatment facility has removed 674 pounds of perchlorate from 7,773 acre-feet of water since it opened in 2011, said Steve Slaten, a NASA remediation project manager. Twenty-three pounds of trichloroethylene, an industrial solvent, have also been removed from the water supply.

The space agency agreed to pay for cleanup after perchlorates from rocket fuel was detected in several area wells. The first rocket test was conduced in 1936 in the Arroyo Seco, in the area where the lab now sits. Most of the waste dumping occurred in the 1940s and '50s.

"There were just open pits that were dug at the surface," said Slaten on Monday during a presentation to the Foothill Municipal Water District. "And all the waste went into these pits. That was toilet water, sink water, runoff water and everything from the lab."

The early pioneers of JPL didn't realize the impact their actions would have on supplying clean drinking water to the region around the lab in the future, he said. The groundwater from the area around JPL flows downhill from mountains above La Cañada Flintridge into Pasadena.

"They put their waste in there and washed it down," said Slaten. "It went out of sight, out of mind. What they didn't know was where it was it was going and what the future impact of those chemicals would be."

NASA has since hunted for perchlorates and solvents from cleaning solutions to correct errors made in the past.

The original time frame for completion of the work was 18 years from the plant's opening, but NASA is looking for ways to speed that up.

At Monk Hill, the toxins are removed from the water in tanks filled with resin beads through an ion exchange system. Fresh beads are exchanged out when perchlorates attach themselves to the old beads. Through a carbon filter process, volatile organic compounds are also removed.

Slaten said perchlorates are pesky to remove.

"When you wash it down with water, the perchlorate is very stable and stays around a long, long time," he said. "It naturally degrades in anaerobic environments but any place where there's plenty of oxygen, it will hang around and not break down naturally."

The good news? The NASA lab does not have a current source that is contributing to regional groundwater contamination.

"We actually have a cleanup program that we can finish in my lifetime," he said.

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