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Hawaii Public Radio – The State Will Use Soiltac to cover up the ash in Lahaina. But what exactly is it? (TPD2310024)

The state will use ‘Soiltac®’ to cover up the ash in Lāhainā. But what exactly is it?

Hawaii Public Radio | By Savannah Harriman-Pote

Published October 11, 2023 at 9:21 AM HST



Roughly 70% of Lāhainā properties have been cleared of hazardous household materials as of Monday, according to the Environmental Protection Agency. But toxic contaminants are still present in the area, especially in the ash of destroyed buildings.

According to the company, Soiltac is “eco-safe, biodegradable, water resistant, ultraviolet ray resistant, non- ammable and is safe for humans, animals, vegetation and marine life.”


That toxic ash likely contains asbestos, lead and arsenic. It continues to pose a health risk to the community, especially when blown around by high winds. Officials are also worried that heavy rains may wash the ash into the ocean and disrupt marine ecosystems.

On Monday, Maui Mayor Richard Bissen approved the EPA’s request to use a soil stabilizer called Soiltac to seal down the ash. It’s the agency’s top choice of adhesive — primarily because it is considered non-toxic.

Soiltac, which is manufactured by the company Soilworks, has a confidential formulation. Tara Fitzgerald, the deputy incident commander for the EPA’s Maui fire response, said that the EPA has been able to review its ingredients to determine that it is safe for use.

Once applied, Soiltac dries clear, which means returning residents will be able to see through it.

“Overall, the sentiment from the communities [was] that they did not want an opaque or colored type of layer on their properties,” Fitzgerald said.

Soiltac has already been applied to certain areas of Kula, and the EPA has been pushing for county approval to use it in Lāhainā. But some residents and county council members have raised concerns.


File – West Maui residents Debbie Patton and Steve Lawless wear protective clothing to guard them from the toxic ash in their search for remnants on September 25, 2023 in Lāhainā.


Testifiers shared uncertainty about the use of Soiltac before the Maui County Council last week. One key point of concern was whether Soiltac could break down into microplastics. Soilworks CEO Chad Falkenberg refuted that idea.

“Soiltac is environmentally and ecologically safe,” Falkenberg stated during the meeting. “It does not degrade into toxic microplastics.”

Fitzgerald likewise maintained that Soiltac is safe. She then reiterated that the real threat to the environment is contaminants present in the ash.

“We should recognize that the ash contains microplastics. It was burned buildings, which have a ton of plastic, so we should expect that microplastics are in that ash,” Fitzgerald said.

Councilmember Keani Rawlins-Fernandez expressed frustration at the EPA and other agencies’ communication about Soiltac, saying that they did little to quell residents’ concerns and correct misinformation early on.

“In the absence of clear communication, again, there’s just a lot of fear,” Rawlins- Fernandez said.

With Soiltac now approved for use, the EPA estimates that it will take about a month to complete the application in Lāhainā. Fitzgerald said there’s no time to waste, as the approaching winter weather makes rain more likely.

“We want to get it covered as soon as possible,” Fitzgerald said.


Savannah Harriman-Pote

 Savannah Harriman-Pote is the energy and climate change reporter. She is also the lead producer of HPR’s This Is Our Hawaiʻi podcast.

See stories by Savannah Harriman-Pote

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