The state Department of Health has fined the Puna Geothermal Venture in Pohoiki on the Big Island $23,700 for emission and notification violations related to the release of hydrogen sulfide during Tropical Storm Iselle in August. 

The clean-air branch of the DOH penalized the plant in a notice and finding of violation Jan. 7 for the failure of PGV’s pressure release valve, its failure to submit on time a report about the release, and the loss of operation of the plant’s monitoring systems during the time of the emission.

The geothermal plant is reviewing the citation, said Michael Kaleikini, senior director for Hawaiian affairs at Ormat Technologies, the company that operates Puna Geothermal Venture. 

"PGV recently received the notice and finding of violation, and we are still assessing the claims made by DOH," he said. 

From approximately 7:25 to 9:18 p.m. Aug. 7, a pressure release valve failure resulted in the release of 38 pounds of hydrogen sulfide into the atmosphere from the geothermal plant.

The plant tripped offline after it lost its ability to push power off-site into the grid when transmission lines were downed by fallen trees. PGV had to relieve pressure by sending a plume of geothermal fluid that had high concentrations of hydrogen sulfide.

One of the release valves — specifically designed to keep the plant from exceeding operating pressure — became stuck and released the high concentration of the gas.

The gas needs to be scrubbed to remove the hydrogen sulfide before being released, a DOH spokeswoman said. 

"Gas with very high concentrations of hydrogen sulfide going into the open, we believe shouldn’t have happened. It should have been going into the backup system. We think all hydrogen sulfide should be scrubbed or abated," she said. 

The state cited PGV for failing to submit on time a written report for the hydrogen sulfide release. It was filed nine days after the deadline. 

The plant also failed to operate and maintain three meteorological monitoring stations and three ambient air quality monitoring stations from Aug. 7 to 14.

The downed monitors make it hard for the department to fully gauge the concentration of hydrogen sulfide in the 38 pounds that was released, said Dr. Barbara Brooks, toxicologist with the state Department of Health.

"Our monitors were down. We really don’t know the levels that were out in the community," Brooks said. "There was some testing done by PGV around the facility, and they reported the levels were low but we don’t know the levels the wind carried out in the community."

The hydrogen sulfide released caused more than 100 people living in the area to report immediate health effects. Some residents reported severe lethargy, nausea, red eyes, burning eyes and respiratory problems.

The Puna Geothermal Venture began operation in 1993 and is the only geothermal plant in the state. It has the capacity to produce up to 38 megawatts of power. In 2013, PGV accounted for about 24 percent of the energy on Hawaii island, said Rhea Lee, administration manager at Hawai’i Electric Light Co.

WHAT IS HYDROGEN SULFIDE?

>> A flammable, colorless gas that smells like rotten eggs

>> It is heavier than air and will sink, making it difficult to detect.

>> Danger depends on how much and how long someone is exposed to it.

>> Relatively low levels cause eye irritation and throat irritation.

>> People have reported vomiting after exposure. 

>> People can die from very high concentrations of exposure. 

Source: Dr. Barbara Brooks, toxicologist with the state Department of Health