College Station officials have given the all-clear for residents to return to the Chimney Hill neighborhood after they were evacuated.
Residents smelled an odor around 7:30 p.m. Tuesday night, and when first responders arrived on scene, they determined the substance causing the odor could be dangerous.
It was calls from residents in the Chimney Hill area that prompted the arrival of first responders. John Anderson and his wife were out walking their dogs.
"We smelled this real powerful smell," Anderson said. "At first, I thought it was gasoline. Then, I went ahead and called the fire department, it was so strong."
Fire officials took readings from the storm sewers in the area where the smell was eminating.
"As they went further along the system to take readings, it turned out it was under a fairly large number of homes over here," said Bart Humphreys, a spokesman for the College Station Fire Department.
Officials determined the odor could be from a volatile, flammable chemical, and began evacuating an estimated 20 homes on a pair of cul-de-sacs off Chimney Hill.
Through the late hours of Tuesday night, crews worked to figure out what the substance was, eventually determining it was a paint-related chemical, a hydrocarbon solvent. Humphreys said air was pumped into the storm sewers to neutralize the chemical, and just after 1 a.m., their readings normalized.
"This particular branch of the storm sewer exits into a live creek very close to where we are, so we definitely don't want to get anything into the environment," Humphreys said.
Residents were taken to a pair of hotels for the evening after being evacuated, a process both sides said went very smoothly.
"They were apologetic for inconveniencing us, which I thought was very nice, but they didn't really have to apologize," Anderson said.
"Citizens were very cooperative," Humphreys said. "They understood exactly what we were trying to do, and it was for their safety."
Officials now turn their attention to finding out how the chemical made its way into the sewers in the first place.