Plans to redevelop a public housing complex in Hilo have been suspended after workers found high levels of arsenic, lead and chlordane in the soil that have likely persisted for decades.

The Lanakila Public Housing project was a priority of the late Sen. Gil Kahele, who grew up in the housing and was successful in securing the release of $7.5 million in funding for redevelopment under former Gov. Neil Abercrombie.

But after crews began work on the project, samples showed elevated levels of the chemicals, which health officials say are likely from lead paint and termiticides that were banned in the 1970s, but can persist in the soil for decades.

“The housing project is something that is really, really needed in Hilo, which is dealing with growing homelessness,” said Sen. Kai Kahele, Gil Kahele’s son, who was appointed to fill his late father’s seat earlier this year.

Kahele says he hopes that remediation work on the site can be completed by the end of the year.

Crews have been working to redevelop 1.5 acres of the site, which includes tearing down seven dilapidated homes and building four multi-unit housing structures, with plans to later develop public housing on the entire 29-acre parcel. The site has been vacant for more than a decade.

Sampling has so far taken place only on the 1.5-acre parcel, but testing and remediation will likely be needed for the entire 29 acres, said John Peard, a remediation project manager for the Department of Health’s Hazard Evaluation and Emergency Response Office.

“The concern is the long-term cancer hazard,” Peard said.

Ongoing exposure to arsenic and chlordane is associated with an increased risk of cancer, while lead can lead to neurological problems, particularly in children.

For now to keep people out, health officials have erected fencing and dust matting around the site, which is bound by Kapiolani, Wailoa and Ululani streets.

“We wouldn’t want kids getting in there, sitting on the foundations, digging around the edges or playing with their toys,” Peard said.

Exposure to the soil is particularly hazardous if it is ingested, which can happen when children are playing outside or people eat with unwashed hands. However, chemicals from the soil can also enter the body from dust, according to a Health Department report.

Earlier this month, health officials released a plan for removing the contaminated soil and are seeking public comments on the plan through June 16.

The department is recommending that up to 2 1/2 feet of soil be removed around and under the housing pads and contained in a separate area on the site at a cost of about $45,950 to $124,920.

Some 33 samples were taken at the site, all of which exceeded Health Department safety limits for arsenic. Four samples exceeded safety limits for lead and two samples exceeded chlordane limits.

Arsenic samples were as high as 45 times the state’s safe limit, known as an environmental action level. However, Peard said that because of the high levels of iron in Hawaii soil, which tightly binds with arsenic, the overall risk to humans is significantly reduced. Still, he said the levels were too high to be safe for residents.

Arsenic is commonly found in the soils in Hawaii, particularly on Hawaii island, because of its use on sugar plantations. But in the case of the Lanakila public housing, Peard said it’s likely that arsenic was sprayed as a termiticide underneath and around the foundations of homes. He said the chemical was broadly used for insect and rat control.