Calhoun County Sheriff Vernon Morris said Friday afternoon that the leak in an anhydrous ammonia pipeline near Hampton was under control, and people who had evacuated were being allowed to return to their homes.
The announcement came shortly after Dave Parker, a spokesman for the Arkansas Department of Transportation, announced that U.S. 167 through the county reopened to traffic.
A 9½-mile section of U.S. 278 in the county had also been closed. The department announced that closure at 9:25 p.m. Thursday, and announced its reopening shortly after 2 a.m. Friday.
About 180 homes in Hampton were evacuated Thursday night after a "trackhoe" ruptured an anhydrous ammonia pipeline, said Calhoun County Sheriff Vernon Morris.
"It's a very serious situation," Morris said Friday morning.
According to the Centers for Disease Control and Prevention, ammonia is a "lung-damaging agent."
"Ammonia is a toxic gas or liquid that, when concentrated, is corrosive to tissues upon contact," according to the center. "Exposure to ammonia in sufficient quantities can be fatal."
Ammonia is used in manufacturing, refrigeration and agriculture (as a fertilizer), according to the center.
Morris said the trackhoe, also known as an excavator, was being operated at Arkansas Gravel Co. at its quarry about three miles southeast of Hampton.
He said 30 homes were initially evacuated, then another 150 as wind took the ammonia from the gravel quarry into southwest Hampton.
Morris said some people evacuated to First Baptist Church in Hampton or the Fordyce Civic Center. Others went to Warren or Camden.
Morris said the air quality in Hampton is being closely monitored today.
"We're waiting on the air quality to clear," he said.
Morris said he hopes to have people from the second evacuation back in those 150 homes tonight, but it may take longer for the first 30 homes that were evacuated.
Morris said the pipeline was ruptured at about 6:45 p.m. Thursday. When contacted at about 10:30 p.m. Thursday, LaTresha Woodruff, public information officer for the Arkansas Division of Emergency Management, said the leak had been contained.
A 24-mile section of U.S. 167 remained closed this morning because of the ammonia leak, according to the Arkansas Department of Transportation. The closed section of U.S. 167 is from Arkansas 274 north of Hampton to Arkansas 335 south of the town.
This story has been updated. It was originally published at 12:07 p.m. under the headline "180 homes evacuated after ammonia pipeline break in Calhoun County."