On muggy days when the wind blows in from the south, the odor from Kailua Wastewater Treatment Plant wafts into 'Aikahi Elementary School.

"Sometimes it's like a strong chemical, other times it's the (hydrogen sulfide) rotten-egg smell and other times a combination of both," said school administrative assistant Chris Soares, noting there's no air conditioning in classrooms, only wall-mounted and standing fans. "When it's very stinky, we get about 15-20 kids complaining of sore stomach and headache."

The state Health Department's Clean Air Branch yesterday fined the city's Kailua Wastewater Treatment Plant, at 95 Kane'ohe Bay Drive, $177,600 for eight odor-control system and 15 fence-line emission violations from January through July of this year. The violations were self-reported by Environmental Services' Wastewater Treatment & Disposal officials and the city has been granted a hearing on the matter, said state Clean Air Branch enforcement supervisor Jill Stensrud.

Fines are sometimes negotiated during hearings, Stensrud said, adding that whatever is collected by the state will go into a special fund used for environmental cleanup efforts.

Four of the city's eight treatment plants — Kailua, Sand Island, Wai'anae and Honouliuli — are required under the federal Clean Water Act to self-report violations to the state because they discharge into the ocean, said Kevin Nakamura, the Wastewater Treatment & Disposal's windward region operations supervisor.

The self-reporting and fines paid to the state process puzzle Soares, who has lived in the Kalaheo Hillside subdivision on 'Ilihau Street near 'Aikahi Elementary for 30 years. "I feel as a taxpayer the (fine) money should be used for remedies at the plant," she said. "You shouldn't take money away from the problem. They need it to make fixes."

The hearing process can be slow-moving. The state and city, for example, are still meeting on a $542,000 fine issued last October for violations at the Sand Island Wastewater Treatment Plant.

Stensrud said the odor-control system permit limits hydrogen sulfide emissions at the Kailua plant to 0.25 parts per million. The eight violations reported by the city ranged from 0.26 to 16 parts per million. The highest recorded emission occurred on June 10. The emission limit at the fence line is 0.025 parts per million and the 15 violations cited ranged from 0.026 to 0.071 parts per million, Stensrud said.

Stensrud said that since July the city has been working on ways to correct the problems that occurred earlier in the year. Aside from mechanical problems, Nakamura said, "There are some aspects that we could be more diligent on, such as preventive maintenance, but we do the best we can with the resources — in particular, manpower — that we have."

Nakamura said odors are a part of any wastewater plant, but the city has hired a contractor to look at ways to better manage foul odors at the Kailua facility.

Officials have been cleaning out the odor-control system for 1 1/2 months. While that is being done, the contractor has been asked to evaluate the possibility of connecting ducts from the cleaned-out system to existing 15-foot high bio-towers to see if it can be discharge some of foul air passing through the system, Nakamura said.

When the tanks are emptied for cleaning, odors are discharged because tanks have to be aired out before workers can safely go in and remove the heavy buildup at the bottom, Nakamura said. Discharged odors are particularly bad during this process. "We're asking the contractor to look into building an overhead structure we can use to suck up the foul air before we go in to clean up," he said.

Reach Rod Ohira at rohira@honoluluadvertiser.com.