Geothermal wells sealed

Lava-threatened plant stoppers toxic gases

Lava from the Kilauea volcano pours into the ocean Wednesday near Pahoa, Hawaii.
Lava from the Kilauea volcano pours into the ocean Wednesday near Pahoa, Hawaii.

PAHOA, Hawaii -- Production wells at a geothermal plant under threat by lava flowing from Hawaii's Kilauea volcano have been plugged to prevent toxic gases from seeping out.

Lava from a nearby, new volcanic vent entered, then stalled, on the 815-acre property where the Puna Geothermal Venture wells occupy about 40 acres. Residents have been concerned about hazards if the lava flowed over the plant's facilities, or if heat generated would interact with various chemicals used on-site.

Ten wells were "quenched" by cooling them with enough cold water to counter the pressure of volcanic steam coming from below, Hawaii Gov. David Ige said. The last well was plugged with mud, because it had remained hot despite the infusion of water. Metal plugs in the wells, which run as deep as 8,000 feet underground, are an additional stopgap measure.

"All wells are stable at this point," Ige said. County officials are also monitoring various gases that may leak into the atmosphere.

A spike in gas levels could prompt a mass evacuation, said Hawaii County Civil Defense Administrator Talmadge Magno. Officials, however, have not discussed specific scenarios that would lead to such an emergency.

Wendy Stovall, a scientist with the U.S. Geological Survey, said Wednesday that lava spatter from a volcanic vent was forming a wall that was helping protect the plant.

Lava from that vent was shooting farther into the air and producing the highest lava wall of all the vents, which was blocking molten rock from flowing north toward the plant.

The volcano has opened more than 20 vents in the ground that have released lava, sulfur dioxide and steam. The lava has been pouring down the flank of the volcano and into the ocean miles away.

Elsewhere on Hawaii's Big Island, blue flames from burning methane sprouted from cracks in the pavement in the Leilani Estates neighborhood.

The volcano produces methane when hot lava buries and burns plants and trees.

"The methane gas will flow through the ground, through the cracks that are already existing, and will come up wherever there's a place for them to come up," Stovall said.

The methane can seep through cracks several feet away from the lava. It can also cause explosions when it's ignited while trapped underground. These blasts can toss blocks several feet away, Stovall said.

Hawaii County has ordered about 2,000 people to evacuate from Leilani Estates and surrounding neighborhoods since the eruption began May 3.

Puna Geothermal, owned by Nevada's Ormat Technologies, was shut down shortly after Kilauea began spewing lava. The plant harnesses heat and steam from the earth's core to spin turbines to generate power. A flammable gas called pentane is used as part of the process, though officials earlier this month removed 50,000 gallons of it from the plant to reduce the chance of explosions.

The plant has the capacity to produce 38 megawatts of electricity, providing roughly one-quarter of the Big Island's daily energy demand.

Lava destroyed a warehouse near the plant late Monday, bringing the total number of structures overtaken in the past several weeks to nearly 50, including dozens of homes.

Information for this article was contributed by Audrey McAvoy of The Associated Press.

A Section on 05/24/2018

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