A fire that caused a huge plume of black smoke to rise over Mililani last week was accidentally sparked by hot work being performed in a yard, a Honolulu Fire Department spokesman said.

The fire was accidentally ignited by hot work, which sparked a brush fire that spread to stored combustibles, said HFD Capt. Scot Seguirant. He said the damage from the fire was estimated at $850,000.

The fire started at about 12:50 p.m. Sept. 19 in the storage yard for GeoTech Solutions, at 94-840 Lanikuhana Ave. Fifty-eight Honolulu firefighters responded as well as state and federal firefighters.

Firefighters found the blaze was burning stored plastics used for erosion and sediment control.

“The high fuel load and remote water sources in the area posed challenges for firefighters,” Seguirant said in an email. The fire was under control by 5:19 p.m. and fully contained at 10:43 p.m.

During the blaze, a large plume of smoke could be seen from miles away.

No homes were threatened by the fire.