A plant shutdown prompted Puna Geothermal Venture to release hydrogen sulfide as Hurricane Iselle approached Thursday evening.
Darryl Oliveira, Hawaii County Civil Defense administrator, said PGV reported readings as high as 39 parts per billion at the source and 25 ppb a half mile away. The incident occurred at about 8 p.m., according to PGV.
Oliveira said the reported concentrations don’t appear to have presented a safety risk to nearby residents though the storm prevented the Hawaii Fire Department’s hazmat team from responding and taking additional readings.
“It was within limits,” he said, regarding the readings.
Oliveira added, “We don’t know what the maximum levels in the community were and for how long.”
The plant shutdown after transmission lines were disrupted by fallen trees, said Mike Kaleikini, PGV senior director of Hawaiian affairs. The release of steam, which includes hydrogen sulfide, occurs as a safety measure.
“We were well prepared for this,” he said. “Our technicians responded as designed.”
Between 95 and 99 percent of hydrogen sulfide is removed through abatement measures when releases occur, according to PGV.
The release lasted for an hour, though the bulk of the release occurred within the first 10 minutes, Kaleikini said.
The plant remains shutdown as repairs on transmission lines occur, he said.