Honolulu firefighters repaired a faulty valve that caused an ammonia leak at a Campbell Industrial Park power plant and prompted temporary evacuations of nearby businesses Wednesday morning.

Five units with 20 firefighters including a Hazardous Materials team responded to the AES Hawaii power plant at 91-086 Kaomi Loop at about 10:20 a.m. due to a chemical odor coming from a 25,000-gallon ammonia tank.

Ammonia is used at the coal-fired power plant to neutralize greenhouse gas emissions.

In an emailed statement, plant manager Steven Barnoski said, “During routine maintenance on a storage tank, one of the valves failed, resulting in an ammonia leak.”

AES immediately implemented emergency procedures, including notifying first responders and nearby businesses, evacuating personnel at the plant and deploying employees with monitors to measure the air quality, he said.

Firefighters also evacuated about 50 people from businesses downwind of the power plant until they replaced the faulty valve.

Firefighters repaired the leak by 11:30 a.m., according to Honolulu Fire spokesman Capt. Scot Seguirant.

Barnoski said, “The situation has been safely resolved. We are grateful for the Honolulu Fire Department’s quick response and assistance.”

No injuries were reported.