Eleven students at a private school in Kailua were taken to the hospital yesterday after they were overcome by a strong sewage odor.

Emergency crews were sent to Redemption Academy, at 355 N. Kainalu Drive, at about 10:50 a.m. after students complained of dizziness, headaches and nausea. The students, ages 9 to 18, were taken by ambulance to Castle Medical Center, where they were treated and released, said Bryan Cheplic, spokesman with the city Department of Emergency Services.

One teacher drove herself to Castle and also was treated and released, Cheplic said.

School officials could not be reached for comment yesterday.

The source of the odor was traced to a pump truck that had discharged wastewater in a nearby manhole, city spokesman Bill Brennan said. He said the company was contracted by the city, but he did not know what kind of work was being performed.

Cheplic said school staff noticed a strong sulfuric odor when they arrived at the school yesterday morning.

"From my understanding, the accountant said she was one of the first to get to school, and that was about 8-something (a.m.), and the odor was pretty bad, but it wasn't overwhelming," Cheplic said. "Progressively over the next two hours it got really, really bad to the point where it was overwhelming and that's when they started calling 911."

Two ambulances and the Fire Department responded to the school. No one appeared to be seriously ill, but 11 students were sent to the hospital as a precaution, Cheplic said.

"Since it's children, we will always err on the side of caution," Cheplic said. "We want to make sure there's no long-lasting effects. We want to really make sure that the kids are OK."

Brennan said the city's Department of Environmental Services will investigate the incident to see if the pump truck driver was following procedures.

"Usually they take it to a pump station or a treatment plant or something and do it there," Brennan said. "It's unusual for these pumper trucks to dewater into a manhole."

Cheplic said the school's staff and students were "really traumatized" by the incident.

"It was hard to speak to anybody out there," he said.

Redemption Academy is a nondenominational Christian school that has students in preschool through high school. The academy, which is part of Redemption Bible College, opened in 1978 as The Good Shepherd School and was renamed Redemption Academy in 1980.

Reach Curtis Lum at culum@honoluluadvertiser.com.