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Rebuilding from the Ground Up: Soil Recovery After Wildfires

Published May 13, 2025

[…and reducing Environmental Risk to acceptable levels]

Recently, I had a conversation with Dr. Stephen Baruch and Dr. Edward Faeder about the state of home gardens and soils in the fire-ravaged areas of Los Angeles. The outlook is concerning, with devastating reports echoed by The Los Angeles Times ^[1],[2] and Daily News ^[3]. They outlined the degradation of soil quality and the impact on flowers, vegetables, and the overall health of home gardens. But they also offered hope, sharing steps homeowners can take to revive their soil.

What’s Being Done — and What’s Not

The U.S. Army Corps of Engineers has stepped up to remove the top 5–6 inches of contaminated soil from fire-damaged properties. While this reduces the risk of inhaling or coming into contact with toxic debris, it’s a blunt tool: no soil testing is being conducted beforehand. Removing layers of soil without identifying the specific toxicants means valuable topsoil — the life force for gardens — is lost alongside contaminants.

The real issue is that the underlying soils are often sterile — stripped of nutrients and loaded with heavy metals like lead and arsenic (metal like), remnants of electronics, furniture, and household materials melted by fire temperatures exceeding 1500°F. Past data show that even after the first soil removal, about 20% of properties remain contaminated. After the 2018 Camp Fire, for example, over 4,200 properties failed to meet safety standards after the initial cleanup.

Federal agencies like FEMA claim that scraping 3–6 inches is enough to protect public health, but there are troubling inconsistencies with that approach. In the aftermath of the Lahaina fires in Hawaii, deeper soil removal, up to 12 inches was authorized, acknowledging deeper contamination was present.

Why Soil Testing Matters

Testing has been a major concern. Without it, families living near burn zones remain vulnerable. The Los Angeles County Department of Public Health recently found elevated lead levels in soils downwind of the Eaton Fire, putting children and pregnant women especially at risk. Lead exposure in young children can cause developmental delays, learning issues, and lower IQs. Arsenic, another carcinogen found both naturally and from human activities, complicates matters even further.

According to experts, homeowners ideally should scrape and replace their topsoil, but if that’s financially unfeasible, simply adding a new layer of clean topsoil can help dilute remaining contaminants. Planting grass can also stabilize the soil and prevent toxic dust from becoming airborne.

In the meantime, basic precautions are essential:

• Wash hands after spending time outdoors.
• Remove shoes before entering the house.
• Use HEPA air filters and/or carbon air filters inside the home. Change The Filters As Recommended.

A Community-Led Effort for Testing

Recognizing the gap left by federal agencies, the R & S Kayne Foundation has committed $1 million to fund soil and air testing in fire-affected zones. Working alongside UCLA, Loyola Marymount University, and Purdue University, their project — Community Action Project Los Angeles (CAP.LA) — is already sampling soils from more than 1,200 homes.

Residents can have their soil tested for free by contacting info@cap.la or calling 1-800-LA-4-LEAD to schedule an appointment through Quest Labs. CAP.LA is also collaborating with the city of Pasadena to test soil at local parks.

UCLA Professor Sanjay Mohanty, who is leading the CAP.LA soil sampling team, does an initial field scan for heavy metals like lead, using handheld X-ray devices, followed by deeper soil core samples to detect volatile organic compounds and polycyclic aromatic hydrocarbons (PAHs). [Halogenated aromatic hydrocarbons and other compounds should be scanned as well.]

Rebuilding Healthy Soil: Remedies and Actions

Even after cleanup efforts, the soil’s chemistry may not be suitable for planting. The Los Angeles Times^[1] conducted pre-scrape soil tests in gardens and found widespread high pH levels, meaning soils are overly alkaline — a direct result of ash from the fires.

Solutions for alkaline soils:

• Add gypsum to neutralize the pH.
• Avoid using crushed concrete in gardens.

Managing heavy metals like lead and arsenic:

• Conduct metals testing, especially near older structures likely to have used lead-based paints or contaminated fertilizers.
• Implement phytoremediation — planting sunflowers, corn, or daikon radishes to pull toxins from the soil (though these plants should not be consumed).
• Sheet mulch: Lay down wet cardboard topped with 4–6 inches of wood chips.
• Use zeolite or biochar: These materials trap heavy metals and improve soil fertility. A 20×20-foot yard would need roughly 50 pounds of zeolite.
• Grow fruit trees: Studies suggest toxins accumulate in the wood, not the fruit.

Building raised plant beds for eatable consumption:

• Add new soil and compost to create clean, nutrient-rich environments for growing food safely.
• Make beds at least 1–2 feet deep to keep plant roots away from contaminated soils.

Looking Ahead

The road to restoring soil health after a wildfire is complex but not impossible. Community-led initiatives like CAP.LA are crucial, filling in where government agencies fall short. As thousands of residents seek soil testing, the need for continued education, remediation, and long-term monitoring is greater than ever.

If your home is in a burn area — or even nearby — now is the time to act. Test your soil, implement protective measures, and invest in rebuilding healthy, vibrant earth beneath your feet. There’s truly no time like the present. And check the results, after cleanup to see if your yard is truly safe.

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¹ Los Angeles Times, “Polluted soil is all over L.A. Here’s how to fix it, even if your home didn’t burn” By Jeanette Marantos, April 24, 2025.

² Los Angeles Times, “When FEMA failed to test soil for toxic substances after the L.A. fires, The Times had it done. The results were alarming” By Tony Briscoe, Noah Haggerty and Hayley Smith, May 4, 2025.

³ Los Angeles Daily News, “With Feds Not Doing So, UCLA, A Private Foundation Step In To Test Soil In Fire Zones” By Steve Scauzillo, April 21, 2025.