The steam release at Puna Geothermal Venture earlier this month was well within safety limits for hydrogen sulfide, according to the state Department of Health.
The Aug. 7 release occurred as Tropical Storm Iselle began hitting Puna, exasperating concerns for some nearby residents who said they couldn’t leave their homes due to downed trees.
But Gary Gill, environmental health deputy director, said Friday there is no reason to believe hydrogen sulfide levels came close to causing harm.
The release occurred as a safety measure when the plant shut down after being disconnected from transmission lines due to the storm.
Without power, PGV’s fence line monitors and DOH’s monitor near the plant also went offline. PGV reported that a handheld monitor detected a peak hydrogen sulfide reading of 25 parts per billion at the fence line, which didn’t put it over its limit of 25 ppb on an average hourly basis.
“If those readings are accurate, given that the concentration is very low, and given the assumption that winds were very high during this period of time, one would not expect any adverse health effects to have been caused by the release as we understand it,” Gill said.
He said his staff is still investigating PGV’s incident report and he has not seen an estimate for how much hydrogen sulfide was released, but he wasn’t expecting it to be substantial based on the plant’s output and previous releases.
The 38-megawatt power plant was running at about 80 percent capacity when the release occurred, according to a plant spokesman. PGV has taken some criticism from neighbors who said it should have shut down completely prior to the storm knowing that a release might happen.
Several have also alleged health affects from the incident, according to Puna Pono Alliance, including rashes, sore throats, headaches and at least one person said they went unconscious.
Gill estimated it would take 500,000 ppb of hydrogen sulfide to cause unconsciousness.
“At the level of exposure that was possible, we would not expect anyone to lose consciousness,” he said.
The Occupational Safety and Health Administration limits workplace exposure to 10,000 ppb, according to PGV.
None of the seven employees working at the time reported health impacts, a plant spokesman said.
Members of Puna Pono Alliance and other geothermal critics have said they believe monitoring is inadequate and doesn’t provide a full assessment.
Gill said DOH staff confer with doctors regarding cases they see. He said he could not comment whether that has occurred regarding complaints from this incident due to privacy concerns but also stated it was his understanding that those who “have been seen by a doctor have been found to be normal.”
A Puna Pono Alliance representative said the group is compiling video testimony from those who say they were impacted by the release. At least 15 had provided testimony as of Wednesday.
In response to the concerns, U.S. Sen. Brian Schatz wrote a letter Aug. 14 to Environmental Protection Agency Administrator Gina McCarthy and U.S. Centers for Disease Control and Prevention Director Tom Frieden requesting they help diagnose and treat any health impacts and ensure emissions are identified and curbed.
He had not received a response as of Friday, according to his staff.
Email Tom Callis at tcallis@hawaii tribune-herald.com.