Omaha's problem with lead-contaminated soil developed over the course of the 120 years that lead was refined on the city's riverfront.
Lead is a ubiquitous contaminant, so the city's problems were compounded by lead dust from deteriorating house paint, exhaust from vehicles powered by leaded gasoline and other sources.
Lead remains a problem in soil because, unlike some contaminants, it doesn't break loose from the dirt and travel with water. Instead, it binds tightly to soil particles.
And for that reason, a century-plus of rain and snow did little to wash away the problem or push it deeper into the soil profile.
Instead, the lead has remained in the upper few inches of Omaha yards, which is why the EPA cleanup has largely involved the top 12 inches of yards.
EPA testing determined that soil in the Omaha area would normally have about 26 parts of lead per million parts of dirt. But Omaha yards tested much higher, some well above 1,000 parts per million. The agency set the cleanup level at 400 parts per million.
A peculiarity of the lead cleanup is that it hasn't extended into those Council Bluffs neighborhoods that are directly east of Omaha's former smelters.
In soil testing in Council Bluffs, the Environmental Protection Agency couldn't find the same traces of smelter contamination it found in Omaha.
One soil scientist theorized that flooding from the Missouri River covered over those yards.
Source: Omaha World-Herald archives
Omaha closer to getting the lead out
The numbers coming out of Omaha in the late 1990s were alarming.
About 20 percent of Douglas County children were testing high for lead in their blood. The national average was closer to 4 percent.
In 1999, the Environmental Protection Agency began what would become the largest and fastest cleanup of lead-contaminated yards in history.
Omaha's lead problem wasn't surprising. The city's riverfront was a hub for lead processing from 1871 until 1997.
The cleanup marked a milestone recently when Aaron Ferer & Sons became the final company to settle.
All told, the EPA has collected $262.5 million in settlements toward what could be a $400 million cleanup price tag; that total doesn't include the earlier cleanup of the riverfront as part of its redevelopment. The EPA hopes to clean its final yard in 2015.
Children are the most vulnerable to lead, which can dull the intellect and has been linked to delinquency. The cleanup, public education, repairs to lead paint on homes, increased testing and other changes have resulted in a 20-fold drop in Douglas County children testing high for lead.
Who has paid for residential cleanup?
The EPA held five companies liable. All said they weren't responsible, but they agreed to pay more than $260 million in total in settlements.
Metals conglomerate formed in 1899 that included a large lead refinery operating in Omaha since 1871. Asarco closed the refinery in 1997. The site was so contaminated, it was entombed in concrete. It is now a park, the Lewis & Clark Landing, located immediately north of Interstate 480.
UNION PACIFIC RAILROAD CO.
U.P. owned the land where Omaha's large refinery was built and leased the property to Asarco until 1946, when it sold it to the metals company.
Operated a secondary lead smelter and lead battery recycling plant along the Missouri River from 1963 to 1982. The plant, purchased from Aaron Ferer & Sons, was immediately south of Asarco. The site was declared contaminated and cleaned up and is now Heartland of America Park.
NATIONAL LEAD INDUSTRIES
Owned these Omaha facilities: Carter White Lead Co., the Omaha Shot and Lead Works, and the Lawrence Shot and Lead Co.
AARON FERER & SONS
Operated a secondary lead smelter and lead battery recycling plant at Fifth and Farnam Streets from about 1954 to 1963 before selling it to Gould Electronics.
QUESTIONS? Call the EPA's information centers: 402-731-3045 or 402-991-9583