Older homes and homes near busy roadways are considered high risk for contaminated soil from lead paint and leaded gasoline. Although environmental regulations have eliminated these products, lead has an estimated half-life of 1,000 years in a typical residential environment and has been shown to stay near the soil surface, according to the U.S. Environmental Protection Agency (EPA). Homes near industrial areas may also have lead or other heavy metals present in their soil, posing a serious health risk to occupants.
Contaminated soil is most likely to affect the health of young children, who directly consume small amounts of soil while playing or through transfer on children’s toys. Lead is by far the most common soil contaminant in residential areas. And lead poisoning in children carries a laundry list of dangerous potential symptoms, from stunted growth to impaired learning ability.
If you suspect that lead or other heavy metals might be present in your soil, the first thing to do is get the soil tested. The University of Minnesota Extension Department of Soil, Water, and Climate recommends taking between six and twelve subsamples from around the yard and mixing them together. From the mix, a final sample can be drawn for submission to a soil testing facility.
Consult your local regulatory body to determine the permitted levels of lead and other contaminants. The U.S. EPA has deemed 400 parts per million (ppm) or less as safe, but other countries and local municipalities may have lower thresholds.
If toxic levels of lead are present in the soil, basic precautions can be taken immediately. Children and adults should wash their hands after coming in contact with contaminated soil; and children’s toys need to be rinsed after outdoor use. Adding doormats and stepping stones in high traffic walkways will reduce the amount of soil that is tracked into the home.
In some instances, low concentrations of lead-contaminated soil can be contained by completing the steps above and covering affected areas with sod, woodchips, or pavement.
Gardening is possible at lower concentrations by mixing in compost to further dilute the lead concentration and maintaining a high soil pH, which limits the bioavailability of lead to attach to plant molecules. A safer option is to construct raised beds with clean topsoil or place plants in containers. Vegetables should be rinsed thoroughly before eating.
The only way to eliminate lead or heavy metals from soil is to remove the soil itself. This is best done using a environmental remediation contractor that is experienced in contaminated soil removal like RW Collins. Remediation professionals will remove the affected soil and seal off what cannot physically be removed with a barrier. The job is finished by filling in the site with clean topsoil.
Some jurisdictions may require this type of work to be done by a certified remediation contractor, especially on government assisted housing or government financed loans.
Remediating the contaminated soil is also an important step to protect against liability if the homeowner is planning to sell a home or is managing a rental property.
Chris Schwind is a freelance technical writer and Principal of Schwind Communications, a firm specializing in business-to-business marketing in the construction and tech industries. He regularly writes about green building, architecture and energy efficiency. He has been published in Eco-Structure, Walls & Ceilings Magazine, Wood Design & Building Magazine, Michigan Builder, Wend Magazine, Modern Materials, and Timber Framing. Connect with Chris on Google+, Twitter, and LinkedIn.
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