The South Dakota Department of Public Safety has concluded that the Ringneck Energy Plant explosion in Onida was accidental.
The investigation report indicates two separate explosions occurred in July, attributed to human error during the restart process after a shutdown.
Deputy State Fire Marshal Michael Jones explained that ramping up the restart too quickly and bypassing a valve interlock led to high-proof ethanol in the corn slurry tank, causing ethanol vapors to escape and ignite.
Fortunately, no injuries were reported in the incidents.