Frank Peryea, Washington State University professor emeritus, shows off apples that have been infested by coddling moth caterpillars on an experimental plot at the university’s Tree Fruit Research & Extension Center.

Frank Peryea, Washington State University professor emeritus, shows off apples that have been infested by coddling moth caterpillars on an experimental plot at the university’s Tree Fruit Research & Extension Center.

Tony Schick / OPB/EarthFix

Millions of acres of farm and orchard land in the United States have been converted to residential uses. In some cases, old pesticides could still be in the soil, even from spraying that occurred decades ago.

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The safest way to prevent exposure to lead- and arsenic-contaminated soil is to keep it in orchards, said scientist Frank Peryea. That keeps the soil away from children. It also doesn’t harm the trees or the fruit they grow.

“Unfortunately that’s not the fate of most of these old orchard sites,” Peryea said.

Their fate has become intertwined with suburban sprawl. Views of the Columbia River and rolling foothills make for attractive home lots. And along with homes come schools, public parks and day cares.

Peryea said there are a few simple steps to take if you live on an old orchard property and have contaminated soil.

  • Before entering your home, take your shoes off  to help prevent tracking contaminated dust inside.
  • Always wash your hands after coming indoors. This tip is especially true for children playing outside in the dirt and mud.
  • Keep all of your dirt covered with grass or other groundcover vegetation.
  • Plant gardens in raised beds and be sure to wash and peel your root vegetables, like potatoes and carrots.

These steps can greatly reduce your risk of exposure to contaminated soils. Here are some additional resources for learning what steps you can take:

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“It’s all about risk and how much risk you’re willing to take,” Peryea said.


Special Report

There's more in our report on legacy contamination on former orchards:


The most permanent, and most expensive, solution is to excavate your topsoil and bring in all clean dirt.

A cheaper alternative, Peryea said, is to cover your contaminated soil with a protective weed-barrier fabric, which will serve as a reminder for anyone digging that there is contamination below.

Then cover the barrier with clean dirt. It’s important to know the origins of your clean dirt. Many old orchard sites in Central Washington are now used for fill dirt, which poses a problem for the Department of Ecology when officials try to figure out the exact locations of the contaminated soil.

Plant grass on top of your new dirt, or cover use another ground cover like pea gravel or a hard surface like a patio.  This is known as capping, and it’s how the Department of Ecology cleans up most schools in Central Washington.

Read the full story here.

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