July 23—Seattle Fire Department Hazardous Material Unit responded to an ammonia gas leak at a milk processing plant on the 4000 block of Rainier Avenue South.

The 911 call came in at 7:35 a.m. from workers inside the plant who heard an explosion and saw a cloud of ammonia come from a broken pipe. Approximately 40 workers safely evacuated the plant by the time firefighters first arrived on scene.

The Seattle Fire Department ordered a 2 block evacuation zone as a precaution. The perimeters are South Charleston Street to the North, Rainier Avenue South to the West, South Dakota Street to the South, 37th Avenue South to the East. A strip mall shopping center with a grocery store and day care center were evacuated to the North. 18 Seattle Police Officers assisted with evacuations and rerouting traffic from the area.

Hazardous Material Unit members entered the building and found a broken 4-inch 150 foot long ammonia gas pipe. The pipe was feeding refrigeration units at the milk processing plant. The pipe was shut down and the ammonia gas inside the line drained out.

The initial gas readings inside the plant was 800 parts per million of ammonia at the broken gas line. The initial readings at the door of the plant were 40 parts per million. At the perimeters, the readings were zero parts per million. 300 parts per million of ammonia gas is considered an immediate danger to life and health

Firefighters opened up the plant’s rolling doors and windows to naturally ventilate the gas from the facility.
A large Mobile Ventilation Unit and large fans were brought in to air out the facility.

Paramedics evaluated two Seattle Police Officers for mild symptoms but they did not need treatment.

No other people were treated as of 11:30 a.m.